bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis, Characterization and Catalytic Property Studies for Isoprene Polymerization of Iron Complexes Bearing Unionized Pyridine-Oxime Ligands
Authors: Zhao Mengmeng , Ma Ying , Zhang Xianhui , Wang Liang , Zhu Guangqian , Wang Qinggang
Published: September 2022

Iron complexes of the types [Fe(HL)2Cl2] (Fe1: HL1 = pyridine-2-aldoxime; Fe2: HL2 = 6-methylpyridine-2-aldoxime; Fe3: HL3 = phenyl-2-pyridylketoxime; Fe4: HL4 = picolinaldehyde O-methyl oxime) were prepared and characterized by elemental analysis and IR spectroscopy. The crystal structure of Fe2, determined by single-crystal X-ray diffraction, featured a distorted octahedral coordination of the iron center binding with two ligands of HL2. The X-ray structure and infrared spectral data indicated that pyridine-oxime ligands act as unionized bidentate ligand by coordinating with Npyridine and Noxime. The catalytic performance for isoprene polymerization, catalyzed by these pyridine-oxime-ligated iron complexes, was examined. For a binary catalytic system combined with MAO, complexes Fe1, Fe3 and Fe4 were found to be highly active (up to 6.5 × 106 g/mol·h) in cis-1,4-alt-3,4 enchained polymerization, with average molecular weights in the range of 60–653 kg/mol and narrow PDI values of 1.7–3.5, even with very low amounts of MAO (Al/Fe = 5). Upon activation with [Ph3C][B(C6F5)4]/AlR3 for the ternary catalytic system, theses complexes showed extremely high activities, as well about 98% yield after 2 min, to afford cis-1,4-alt-3,4-polyisoprene with a molecular weight of 140–420 kg/mol.
Highlighting the Importance of Characterization Techniques Employed in Adsorption Using Metal–Organic Frameworks for Water Treatment
Authors: Maponya Thabiso C. , Makgopa Katlego , Somo Thabang R , Modibane Kwena D.
Published: September 2022

The accumulation of toxic heavy metal ions continues to be a global concern due to their adverse effects on the health of human beings and animals. Adsorption technology has always been a preferred method for the removal of these pollutants from wastewater due to its cost-effectiveness and simplicity. Hence, the development of highly efficient adsorbents as a result of the advent of novel materials with interesting structural properties remains to be the ultimate objective to improve the adsorption efficiencies of this method. As such, advanced materials such as metal–organic frameworks (MOFs) that are highly porous crystalline materials have been explored as potential adsorbents for capturing metal ions. However, due to their diverse structures and tuneable surface functionalities, there is a need to find efficient characterization techniques to study their atomic arrangements for a better understanding of their adsorption capabilities on heavy metal ions. Moreover, the existence of various species of heavy metal ions and their ability to form complexes have triggered the need to qualitatively and quantitatively determine their concentrations in the environment. Hence, it is crucial to employ techniques that can provide insight into the structural arrangements in MOF composites as well as their possible interactions with heavy metal ions, to achieve high removal efficiency and adsorption capacities. Thus, this work provides an extensive review and discussion of various techniques such as X-ray diffraction, Brunauer–Emmett–Teller theory, scanning electron microscopy and transmission electron microscopy coupled with energy dispersive spectroscopy, and X-ray photoelectron spectroscopy employed for the characterization of MOF composites before and after their interaction with toxic metal ions. The review further looks into the analytical methods (i.e., inductively coupled plasma mass spectroscopy, ultraviolet-visible spectroscopy, and atomic absorption spectroscopy) used for the quantification of heavy metal ions present in wastewater treatment.
Micronized Recycle Rubber Particles Modified Multifunctional Polymer Composites: Application to Ultrasonic Materials Engineering
Authors: Genovés Vicente , Fariñas María Dolores , Pérez-Aparicio Roberto , Saiz-Rodríguez Leticia , Valentín Juan López , Álvarez-Arenas Tomás Gómez
Published: September 2022

There is a growing interest in multifunctional composites and in the identification of novel applications for recycled materials. In this work, the design and fabrication of multiple particle-loaded polymer composites, including micronized rubber from end-of-life tires, is studied. The integration of these composites as part of ultrasonic transducers can further expand the functionality of the piezoelectric material in the transducer in terms of sensitivity, bandwidth, ringing and axial resolution and help to facilitate the fabrication and use of phantoms for echography. The adopted approach is a multiphase and multiscale one, based on a polymeric matrix with a load of recycled rubber and tungsten powders. A fabrication procedure, compatible with transducer manufacturing, is proposed and successfully used. We also proposed a modelling approach to calculate the complex elastic modulus, the ultrasonic damping and to evaluate the relative influence of particle scattering. It is concluded that it is possible to obtain materials with acoustic impedance in the range 2.35–15.6 MRayl, ultrasound velocity in the range 790–2570 m/s, attenuation at 3 MHz, from 0.96 up to 27 dB/mm with a variation of the attenuation with the frequency following a power law with exponent in the range 1.2–3.2. These ranges of values permit us to obtain most of the material properties demanded in ultrasonic engineering.
Application of Group Method of Data Handling on the Ultimate Conditions’ Prediction of FRP-Confined Concrete Cylinders
Authors: Deng Chubing , Zhang Ruiliang , Xue Xinhua
Published: September 2022

Fiber-reinforced polymer (FRP) is widely used in the field of structural engineering, for example, as a confining material for concrete. The ultimate conditions (i.e., compressive strength and ultimate axial strain) are key factors that need to be considered in the practical applications of FRP-confined concrete cylinders. However, the prediction accuracy of existing confinement models is low and cannot provide an effective reference for practical applications. In this paper, a database containing experimental data of 221 FRP-confined normal concrete cylinder specimens was collected from the available literature, and eleven parameters such as the confining stress, stiffness ratio and strain ratio were selected as the input parameters. Then, a promising machine learning algorithm, i.e., group method of data handling (GMDH), was applied to establish a confinement model. The GMDH model was compared with nine existing models, and the prediction results of these models were evaluated by five comprehensive indicators. The results indicated that the GMDH model had higher prediction accuracy and better stability than existing confinement models, with determination coefficients of 0.97 (compressive strength) and 0.91 (ultimate axial strain). Finally, a convenient graphical user interface (GUI) was developed, which can provide a quick and efficient reference for engineering design and is freely available.
Highly Sensitive Temperature Sensor Based on Cascaded Polymer-Infiltrated Fiber Mach–Zehnder Interferometers Operating near the Dispersion Turning Point
Authors: He Jia , Zhang Fengchan , Xu Xizhen , Du Bin , Wu Jiafeng , Li Zhuoda , Bai Zhiyong , Guo Jinchuan , Wang Yiping , He Jun
Published: September 2022

High-accuracy temperature measurement plays a vital role in biomedical, oceanographic, and photovoltaic industries. Here, a highly sensitive temperature sensor is proposed and demonstrated based on cascaded polymer-infiltrated Mach–Zehnder interferometers (MZIs), operating near the dispersion turning point. The MZI was constructed by splicing a half-pitch graded index fiber (GIF) and two sections of single-mode fiber and creating an inner air cavity based on femtosecond laser micromachining. The UV-curable polymer-infiltrated air cavity functioned as one of the interference arms of MZI, and the residual GIF core functioned as the other. Two MZIs with different cavity lengths and infiltrated with the UV-curable polymers, having the refractive indexes on the different sides of the turning point, were created. Moreover, the effects of the length and the bending way of transmission SMF between the first and the second MZI were studied. As a result, the cascaded MZI temperature sensor exhibits a greatly enhanced temperature sensitivity of −24.86 nm/°C based on wavelength differential detection. The aforementioned result makes it promising for high-accuracy temperature measurements in biomedical, oceanographic, and photovoltaic applications.
Study on the Mechanical and Toughness Behavior of Epoxy Nano-Composites with Zero-Dimensional and Two-Dimensional Nano-Fillers
Authors: Li Xiaodong , Wang Qi , Cui Xu , Feng Xinwen , Teng Fei , Xu Mingyao , Su Weiguo , He Jun
Published: September 2022

The mechanical properties of epoxy resin can be enhanced by adding nanofillers into its matrix. This study researches and compares the impacts of adding nanofillers with different dimensions, including two-dimensional boron nitride and zero-dimensional silica, on the mechanical and toughness properties of epoxy resin. At low fractions (0–2.0 wt%), 2DBN/epoxy composites have a higher Young’s modulus, fracture toughness and critical strain energy release rate compared to SiO2/epoxy composites. However, the workability deteriorated drastically for BN/epoxy composites above a specific nanofiller concentration (2.0–3.0 wt%). BN prevents crack growth by drawing and bridging. SiO2 enhances performance by deflecting the crack direction and forming voids. Additionally, the dimension and content of nanofiller also influence glass transition temperature and storage modulus significantly.
Design and Engineering of Natural Cellulose Fiber-Based Biomaterials with Eucalyptus Essential Oil Retention to Replace Non-Biodegradable Delivery Systems
Authors: Morais Flávia P. , Curto Joana M. R.
Published: September 2022

This work aims at the design and engineering of sustainable biomaterials based on natural fibers to replace non-renewable fiber sources in the development of non-woven delivery systems. Cellulose fibers were used as the main support to produce multi-structured materials with the incorporation of microfibrillated cellulose (MFC) as an additive. A 3D carboxymethylcellulose matrix retaining a natural bioactive product, eucalyptus essential oil, (CMC/EO), with controlled release functionalities, was also applied to these materials using bulk and spray coating methodologies. Additionally, using a 3D modeling and simulation strategy, different interest scenarios were predicted to design new formulations with improved functional properties. Overall, the results showed that MFC provided up to 5% improved strength (+48%) at the expense of reduced softness (−10%) and absorbency (−13%) and presented a good potential to be used as an additive to maximize natural eucalyptus fibers content in formulations. The addition of CMC/EO into formulations’ bulk revealed better strength properties (21–28%), while its surface coating improved absorption (23–25%). This indicated that both application methods can be used in structures proposed for different sustainable applications or a more localized therapy, respectively. This optimization methodology consists of a competitive benefit to produce high-quality functionalized biomaterials for added-value applications.
Poloxamer-Based Hydrogel as Drug Delivery System: How Polymeric Excipients Influence the Chemical-Physical Properties
Authors: Brambilla Elisa , Locarno Silvia , Gallo Salvatore , Orsini Francesco , Pini Carolina , Farronato Marco , Thomaz Douglas Vieira , Lenardi Cristina , Piazzoni Marco , Tartaglia Gianluca
Published: September 2022

Thermogelling amphiphilic block copolymers have been widely investigated in the development of pharmaceutical drug carriers. In particular, thermosensitive gels based on poloxamer 407 (P407) have great potential for periodontal disease treatment, thanks to their ability to be liquid at room temperature and become viscous gels at body temperature. However, some problems, related to short in situ residence time, reduce their feasible clinical use. Thus, in order to improve the effective applicability of these materials, we studied how P407 thermogels are affected by the pH and by the inclusion of different hydrophilic polymers, used as excipients for increasing the gel stiffness. For this scope, a complete chemical-physical characterization of the synthesized gels is provided, in terms of determination of sol-gel transition temperature, viscosity and erosion degree. The data are correlated according to a statistical multivariate approach based on Principal Component Analysis and their mucoadhesion properties are also tested by Tapping mode-Atomic Force Microscopy (TM-AFM) imaging. Finally, we studied how the different P407 formulations are able to influence the release pathway of two antibacterial drugs (i.e., chlorhexidine digluconate and doxycycline hyclate) largely used in oral diseases.
Ultra-Dispersed Powders Produced by High-Temperature Shear-Induced Grinding of Worn-Out Tire and Products of Their Interaction with Hot Bitumen
Authors: Nikol’skii Vadim , Dudareva Tatiana , Krasotkina Irina , Gordeeva Irina , Vetcher Alexandre A. , Botin Alexander
Published: September 2022

Structural features of crumb rubber (CR) particles obtained by grinding on rollers and ultra-disperse powder elastomeric modifiers (PEM) obtained by high-temperature shear-induced grinding (HTSG) of CR or co-grinding with butadiene styrene thermoplastic elastomer (SBS) have been studied by electron and optical microscopy methods. Samples of modified bitumen were obtained at different mixing times (1–40 min) in a wide temperature range (120–180 °C). The products of interaction of PEM with hot bitumen precipitated on filters when washed with solvent from modified bitumen (MB) were studied by scanning electron microscopy (SEM). The self-similarity PEM particles and PEM breakdown fragments in bitumen up to the size of 100–200 nm were noted. The rapid (for 1 min) decomposition of PEM particles into fragments is shown, which is due to the specific structure formed as a result of HTSG. It has been suggested that this fragmentation may be caused by bitumen penetrating deep into the porous particle and breaking it, due to differently directed swelling pressure and precede the classical swelling associated with the penetration of solvent between rubber macromolecules, or occur concurrently with it.
Strong and Lightweight Stereolithographically 3D-Printed Polymer Nanocomposites with Low Friction and High Toughness
Authors: Ávila-López Manuel Alejandro , Bonilla-Cruz José , Méndez-Nonell Juan , Lara-Ceniceros Tania Ernestina
Published: September 2022

Strong and lightweight polymer nanocomposites with low friction, high toughness, and complex shapes were obtained for the first time through an affordable stereolithographic 3D printer, using low amounts of TiO2 nanoparticles. Tridimensional solid structures (i.e., tensile bars, compressive test specimens, gyroid-type structures, and dense lattices) were obtained. Herein, we found that the compressive stress, compressive strain, yield strength, and toughness corresponding to 3D-printed polymer nanocomposites were simultaneously increased—which is uncommon—using low amounts (0.4 wt.%) of TiO2 nanoparticles. Furthermore, we obtained lightweight cylindrical structures exhibiting high resistance to compression with a low friction coefficient (µ~0.2), and the printability of complex and hollow structures was demonstrated.
Dynamic Mechanical Analysis and Ballistic Performance of Kenaf Fiber-Reinforced Epoxy Composites
Authors: da Silva Thuane Teixeira , Silveira Pedro Henrique Poubel Mendonça da , Figueiredo André Ben-Hur da Silva , Monteiro Sérgio Neves , Ribeiro Matheus Pereira , Neuba Lucas de Mendonça , Simonassi Noan Tonini , Garcia Filho Fabio da Costa , Nascimento Lucio Fabio Cassiano
Published: September 2022

Several industry sectors have sought to develop materials that combine lightness, strength and cost-effectiveness. Natural lignocellulosic natural fibers have demonstrated to be efficient in replacing synthetic fibers, owing to several advantages such as costs 50% lower than that of synthetic fibers and promising mechanical specific properties. Polymeric matrix composites that use kenaf fibers as reinforcement have shown strength increases of over 600%. This work aims to evaluate the performance of epoxy matrix composites reinforced with kenaf fibers, by means of dynamic-mechanical analysis (DMA) and ballistic test. Through DMA, it was possible to obtain the curves of storage modulus (E′), loss modulus (E″) and damping factor, Tan δ, of the composites. The variation of E′ displayed an increase from 1540 MPa for the plain epoxy to 6550 MPa for the 30 vol.% kenaf fiber composites, which evidences the increase in viscoelastic stiffness of the composite. The increase in kenaf fiber content induced greater internal friction, resulting in superior E″. The Tan δ was considerably reduced with increasing reinforcement fraction, indicating better interfacial adhesion between the fiber and the matrix. Ballistic tests against 0.22 caliber ammunition revealed similar performance in terms of both residual and limit velocities for plain epoxy and 30 vol.% kenaf fiber composites. These results confirm the use of kenaf fiber as a promising reinforcement of polymer composites for automotive parts and encourage its possible application as a ballistic armor component.
Study on the Discharge Process and Mechanism of Anti-Corrosion Pill Particles in the Oil and Gas Field Wellbore Casing Annulus Based on the Discrete Element Method
Authors: Liu Dongtao , Lu Yuliang , Lin Haichun , Qiao Chunshang , Song Jiming , Chen Shengqian , Yao Zhenhe , Du Kezheng , Yu Yajun
Published: September 2022

This research studies the discharge process and its mechanism using the discrete element method (DEM) with self-developed annular corrosion pill particles and the discharge device as an example in order to optimize the oil and gas field wellbore casing annular corrosion process. The object of study was chosen from four different grid numbers and four different grid widths, and EDEM software was utilized to simulate and assess the pill particle discharge process based on preliminary experimental research. Under five different pill wheel rotation speeds, the effects of the grid number and grid width on the filling amount, filling density, discharge variation coefficient, and compressive force of pill particles were investigated from macroscopic and microscopic viewpoints. The findings reveal that the grid number, grid width, and rotation speed all have a significant impact on pill filling and discharge performance. As a result, the discharge wheel’s structure and operating characteristics were optimized. The discharge wheel performs best when the grid number is 8, the grid width is 75 mm, and the rotation speed is 15 rpm; the pill filling density is 692.26 kg/m3, the discharge variation coefficient is 0.022, and the maximum compressive force is 188 N. This study establishes the groundwork for enhancing wellbore integrity management in oil and gas fields by providing a reference for the optimal design of wellbore casing annular corrosion prevention devices in oil and gas fields.
Preparation and Selection of Best-Performing Fluorescent-Based Tracers for Oil and Gas Downhole Applications
Authors: Khmelnitskiy Vladimir , AlJabri Nouf , Solovyeva Vera
Published: September 2022

Cost-efficient tracers with fast and simple detection and quantification methods at low detection limits via on-site detection is a current industrial target for state-of-the-art tracer tests. To bridge the gap between the desired tracer properties and detection limits, we developed a broad spectrum of robust and cost-efficient fluorescent tags to innovate the current reservoir management practices. We engineered new tracers and extended tracer test applications for on-site real-time well-drilling monitoring to label drill cuttings as they are made at the drill-bit face to improve drill-cuttings depth correlation. These developed fluorescent tracers not only have the low detection limits of fluorescent spectroscopy techniques but also allow for automated detection at minimal concentrations of 0.025–0.037 mol.%. These developed tracers allow us to detect the real-time drilling depth, thereby enhancing hydrocarbon recovery. Thus, the reported innovative fluorescent-based tracing approach would (1) reduce drilling depth correlation uncertainty, (2) optimize well placement, and (3) maximize oil production.
Influencing Factors on Synthesis and Properties of MXene: A Review
Authors: Zhang Lin , Song Weiwei , Liu Hongshi , Ding Hong , Yan Yibo , Chen Ruihan
Published: September 2022

MXene has a unique two-dimensional layered structure, a large specific surface area, and good electrical conductivity, stability, magnetic properties, and mechanical properties. Attributed to its structure and properties, MXene has entered various application fields, such as tumors, antibiotics, batteries, hydrogen storage, sensors, electromagnetic shielding, etc. Studies on MXene are implemented in various fields. The preparation methods, surface functional groups, and the preparation technology of composite materials directly affect the performance of MXene and determine its application fields. As significantly important issues, many influencing factors exist in the preparation process of MXene and the process of composite material design, which directly impact the properties and applications of MXene. This paper investigates and analyzes the factors influencing the preparation, properties, and application of MXene, explores the research progress of MXene, and provides critical insights for synthesizing and modifying effective MXene adsorbents. Moreover, this review discusses the influencing factors on applications, i.e., CO2 reduction, energy storage, heavy metal removal, etc., and compares key factors, including surface modification, pH, reaction time, and adsorption capacity, etc. Furthermore, this review provides an overview on current status and offers recommendations.
Beyond Literal Idolatry: Imagining Faith through Creatively Changing Identities
Authors: Boscaljon Daniel
Published: September 2022

This is Part I of a triptych. It addresses the latent potential of the imagination in constructing a sense of identity. Included is the role of faith in overcoming the obstacles presented by a social imaginary dominated by literal idolatry that leads to unnecessary suffering. The initial foundation examines the process of growth and the role that the imagination plays in the construction of narrative identity—an important part of human development. Literal idolatry interrupts this original process through the creation of a social imaginary that corrupts natural measures for self-correction. At the same time, a creative faith contains the capacity to dislodge the rigid boundaries of literal idolatry. A creative faith narrative identities in ways that open beyond simple coherence and completeness. It can also revitalize social institutions and public spaces. The argument concludes by arguing fictional narratives augment the work of theology in grounding and inspiring creative faith.
Evangelicals and Abolitionist Methodologies
Authors: Smith Andrea
Published: September 2022

The development of the primarily women-of-color-led movement for transformative justice has also shed light on the fact that abolition requires not just the transformation of social relations and place, but the transformations of subjectivity itself. This movement recognizes that violence is not just enacted against oppressed communities but is enacted with them, and hence the line between those who harm and those who face harm is often illusory. The movement for transformative justice—for accountability without disposability—calls on us to create different systems of relationality, which, in turn, transform who we think we are as people. Essentially, we are required to embark on an uncharted journey that will result in the creation of new selves we would not now recognize. Abolition can be seen as a process and a methodology rather than a presumed destination. To identify abolitionist methodologies, it can be helpful to look at unexpected places rather than presume that some spaces and peoples are necessarily more abolitionist than others. Consequently, this essay will look at abolitionism in an unexpected place, Christian evangelicalism.
Divine Omnipotence, Divine Sovereignty and Moral Constraints on the Prevention of Evil: A Reply to Sterba
Authors: Reitan Eric
Published: September 2022

In Is a Good God Logically Possible?, James Sterba uses the analogy of a just political state to develop evil-prevention principles he thinks a good God would follow. With the assumption that God is omnipotent, these principles entail that God would never permit free agents to bring about horrendous evil. But free agents routinely succeed in doing so: entailing a logical incompatibility between the world’s evils and the existence of a good, omnipotent God. I challenge this conclusion by sketching two ways divine omnipotence arguably entails that God would face moral constraints on the prevention of moral evil that human agents and political states do not. If my account is sound, God would be morally precluded from functioning as a sovereign governing authority in the manner of just political states. If this is correct, Sterba’s arguments might be taken to show, not that there is a contradiction between the world’s evil and the existence of a good, almighty God, but that there is a contradiction between the world’s evil and the common theistic belief that such a God is the sovereign ruler of the world.
Korean Buddhist International Aid Work: A Critical Comparison of the Join Together Society and the Global Community Association (Good Hands)
Authors: Park Cheonghwan , Kim Kyungrae
Published: September 2022

This paper critically scrutinizes the history and activities of South Korea’s two largest Buddhist international aid organizations, namely, the Join Together Society, founded in 1991 by Venerable Pomnyun, leader of Korea’s independent Jungto Society order of lay Buddhists, and the Global Community Association (Jiguchon Gongsaenghoe, Good Hands), founded by former Jogye Order president, Venerable Wolju (1935–2021). It examines the origins, organizations, and activities of both organizations, followed by a comparison of their similarities and differences, along with a discussion of their respective relationships to Korean Buddhist mainstream life and the advantages and disadvantages of each. They are significant, not only for the many benefits they have brought to their target communities abroad but also for what they represent to the Korean Buddhist community at home. As the Korean Buddhist establishment continues to grapple with a prolonged crisis of falling membership and loss of relevance within Korea’s increasingly agnostic society, the long-term sustainability of Korean Buddhist international efforts remains an open question. Nevertheless, the two organizations represent new visions for the modes of meaningful Buddhist praxis and engagement with the modern world that have a strong appeal to Korea’s younger, urbanized Buddhist laity. The further support and expansion of such activities by the Buddhist establishment might aid in reversing the current downward trends of belief.
An Analysis of the Optimal Features for Sentinel-1 Oil Spill Datasets Based on an Improved J–M/K-Means Algorithm
Authors: Cheng Lingxiao , Li Ying , Zhang Xiaohui , Xie Ming
Published: September 2022

With the rapid development of world shipping, oil spill accidents such as tanker collisions, illegal sewage discharges, and oil pipeline ruptures occur frequently. As the SAR system expands from single polarization to multipolarization, the Polarmetric Synthetic Aperture Radar (Pol-SAR) system has been widely used in marine oil spill detection. However, in the studies of the oil spill extraction in SAR images, there are some problems that limit large-scale oil spill detection work. As a transition from single-polarized to full-polarized, the dual-polarized system carries some polarization information and can be obtained in large quantities for free, which has become a major breakthrough in solving the problem of large-scale oil spill detection. In order to optimize the multisource features that can be extracted from dual-polarized SAR images, greatly improve the utilization rate of dual-polarized SAR oil spill images under the premise of reducing workload, and ensure the accuracy of marine oil spill extraction, this paper adopts the metric of inter-class separability, the Jeffries–Matusita distance, which improves on the traditional K-means algorithm by focusing on the noise sensitivity defect of the K-means algorithm; the artificial influence of J–M distance in measuring the separability between classes improves the algorithm in three aspects: sample selection, distance calculation, and data evaluation. Finally, using the inter-sample J–M distance of multisource features, the overall accuracy of image segmentation, the F1-score, and the results of correlation analysis between features, three advantageous features and three subdominant features are selected that can be used for marine oil spill detection.
Deep-Learning-Based Method for Estimating Permittivity of Ground-Penetrating Radar Targets
Authors: Wang Hui , Ouyang Shan , Liu Qinghua , Liao Kefei , Zhou Lijun
Published: September 2022

Correctly estimating the relative permittivity of buried targets is crucial for accurately determining the target type, geometric size, and reconstruction of shallow surface geological structures. In order to effectively identify the dielectric properties of buried targets, on the basis of extracting the feature information of B-SCAN images, we propose an inversion method based on a deep neural network (DNN) to estimate the relative permittivity of targets. We first take the physical mechanism of ground-penetrating radar (GPR), working in the reflection measurement mode as the constrain condition, and then design a convolutional neural network (CNN) to extract the feature hyperbola of the underground target, which is used to calculate the buried depth of the target and the relative permittivity of the background medium. We further build a regression network and train the network model with the labeled sample set to estimate the relative permittivity of the target. Tests were carried out on the GPR simulation dataset and the field dataset of underground rainwater pipelines, respectively. The results show that the inversion method has high accuracy in estimating the relative permittivity of the target.
EO4Migration: The Design of an EO-Based Solution in Support of Migrants’ Inclusion and Social-Cohesion Policies
Authors: Aquilino Mariella , Tarantino Cristina , Athanasopoulou Eleni , Gerasopoulos Evangelos , Blonda Palma , Quattrone Giuliana , Fuina Silvana , Adamo Maria
Published: September 2022

The purpose of this research is to demonstrate the strong potential of Earth-observation (EO) data and techniques in support of migration policies, and to propose actions to fill the existing structural gaps. The work was carried out within the “Smart URBan Solutions for air quality, disasters and city growth” (SMURBS, ERA-PLANET/H2020) project. The novelties introduced by the implemented solutions are based on the exploitation and synergy of data from different EO platforms (satellite, aerial, and in situ). The migration theme is approached from different perspectives. Among these, this study focuses on the design process of an EO-based solution for tailoring and monitoring the SDG 11 indicators in support of those stakeholders involved in migration issues, evaluating the consistency of the obtained results by their compliance with the pursued objective and the current policy framework. Considering the city of Bari (southern Italy) as a case study, significant conclusions were derived with respect to good practices and obstacles during the implementation and application phases. These were considered to deliver an EO-based proposal to address migrants’ inclusion in urban areas, and to unfold the steps needed for replicating the solution in other cities within and outside Europe in a standardized manner.
Spatio-Temporal Patterns of Ecosystem Services Provided by Urban Green Spaces and Their Equity along Urban–Rural Gradients in the Xi’an Metropolitan Area, China
Authors: Peng Lixian , Zhang Liwei , Li Xupu , Wang Pengtao , Zhao Wudong , Wang Zhuangzhuang , Jiao Lei , Wang Hao
Published: September 2022

Urban green spaces (UGSs) are indispensable for providing various ecosystem services (ESs) to society and city-dwellers. The equitable allocation of ESs provided by UGSs is a prerequisite for maintaining urban sustainability and human well-being. However, empirical studies have assessed the dynamics of UGS equity from ES facets, while neglecting to strengthen integrated evaluation indicators and coupled spatially explicit models. A framework was developed in this study to assess the spatio-temporal patterns of ESs provided by UGSs and their equity based on models of the Intelligent Urban Ecosystem Management System, location entropy, and the Gini coefficient. The results indicated that with urban spatial expansion, in each concentric circle, the values of three ES averages were generally the lowest in the megacity (Xi’an), and the values of carbon sequestration and the recreation averages in the medium-sized cities (Baoji and Xianyang) were also lower than in the small-sized city (Tongchuan). The inequity of ESs provided by UGSs was exacerbated from 2000 to 2020 in the Xi’an Metropolitan Area. The ES equity was the worst in Xi’an and the best in Tongchuan. Areas with extremely low CR location entropy occupied 67.01% in 2020. As cities spatially expanded, areas with extremely low ES location entropy generally increased in 2020. Additionally, the zero-value area of the ES Gini coefficient in Xi’an was the largest from 2000 to 2020. The ES Gini values mostly increased in the same concentric circle of each city in 2020, which demonstrates that equity declined. Spatial equity could be improved by diversifying UGS structures, promoting spatial matching between the ES supply and beneficiaries’ demands, and integrating UGSs into any available space in future UGS planning. The findings of the study could offer insights for optimizing the equitable provision of UGS resources and the targeted planning of urban greening.
An Efficient Method for Detection and Quantitation of Underwater Gas Leakage Based on a 300-kHz Multibeam Sonar
Authors: Zhang Wanyuan , Zhou Tian , Li Jianghui , Xu Chao
Published: September 2022

In recent years, multibeam sonar has become the most effective and sensitive tool for the detection and quantitation of underwater gas leakage and its rise through the water column. Motivated by recent research, this paper presents an efficient method for the detection and quantitation of gas leakage based on a 300-kHz multibeam sonar. In the proposed gas leakage detection method based on multibeam sonar water column images, not only the backscattering strength of the gas bubbles but also the size and aspect ratio of a gas plume are used to isolate interference objects. This paper also presents a volume-scattering strength optimization model to estimate the gas flux. The bubble size distribution, volume, and flux of gas leaks are determined by matching the theoretical and measured values of the volume-scattering strength of the gas bubbles. The efficiency and effectiveness of the proposed method have been verified by a case study at the artificial gas leakage site in the northern South China Sea. The results show that the leaking gas flux is approximately between 29.39 L/min and 56.43 L/min under a bubble radius ranging from 1 mm to 12 mm. The estimated results are in good agreement with the recorded data (32–67 L/min) for gas leaks generated by an air compressor. The experimental results demonstrate that the proposed method can achieve effective and accurate detection and quantitation of gas leakages.
S2-PCM: Super-Resolution Structural Point Cloud Matching for High-Accuracy Video-SAR Image Registration
Authors: Xie Zhikun , Shi Jun , Zhou Yihang , Yang Xiaqing , Guo Wenxuan , Zhang Xiaoling
Published: September 2022

In this paper, the super-resolution structural point cloud matching (S2-PCM) framework is proposed for video synthetic aperture radar (SAR) inter-frame registration, which consists of a feature recurrence super-resolution network (FRSR-Net), structural point cloud extraction network (SPCE-Net) and robust point matching network (RPM-Net). FRSR-Net is implemented by integrating the feature recurrence structure and residual dense block (RDB) for super-resolution enhancement, SPCE-Net is implemented by training a U-Net with data augmentation, and RPM-Net is applied for robust point cloud matching. Experimental results show that compared with the classical SIFT-like algorithms, S2-PCM achieves higher registration accuracy for video-SAR images under diverse evaluation metrics, such as mutual information (MI), normalized mutual information (NMI), entropy correlation coefficient (ECC), structural similarity (SSIM), etc. The proposed FRSR-Net can significantly improve the quality of video-SAR images and point cloud extraction accuracy. Combining FRSR-Net with S2-PCM, we can obtain higher inter-frame registration accuracy, which is crucial for moving target detection and shadow tracking.
Remote Sensing of Land Surface Phenology: Editorial
Authors: Ma Xuanlong , Jin Jiaxin , Zhu Xiaolin , Zhou Yuke , Xie Qiaoyun
Published: September 2022

Land surface phenology (LSP) is an important research field in terrestrial remote sensing and has become an indispensable approach in global change research, as evidenced by many important scientific findings supported by LSP in recent decades [...]
Assessment of FY-2G, FY-4A, and Himawari-8 Atmospheric Motion Vectors over Southeast Asia and Their Assimilating Impact on the Forecasts of Tropical Cyclone PABUK
Authors: Yiemwech Jaral , Chen Yaodeng , Shen Jie , Wang Yuanbing , Alriah Mohamed Abdallah Ahmed
Published: September 2022

The spatial coverage of atmospheric motion vectors (AMVs) over Southeast Asia (SEA) is mainly covered by the Himawari-8 (HIMA-8) and FengYun-2 (FY-2) series satellites in the Global Telecommunication System (GTS). With the launch of FengYun-4A (FY-4A), a new Chinese geostationary satellite, AMVs have enhanced the spatial and temporal resolution data along with allowing for more options of the spectral channels than the FY-2G. This study focuses on the preliminary quality assessments of the FY-2G, FY-4A and HIMA-8 AMVs during a three-month monsoon period, as well as the impact of assimilating AMVs on the numerical weather prediction (NWP) model over SEA. The results show that the qualities of the AMVs from the FY-2G and FY-4A are sensitive to different quality indicator (QI) values, but this is not the case for the HIMA-8. For QI values at 85%, FY-2G and FY-4A AMVs had a monthly mean feature in the monsoon period that were quite comparable to HIMA-8 AMVs, with a few exceptions in this area when three sets of AMVs were validated against NCEP/FNL operational global analysis data; however, the qualities of the AMVs from HIMA-8 were better overall than those from FY-2G and FY-4A. In addition, four experiments were conducted with and without an assimilation of AMVs with a QI at 85% available from FY-2G, FY-4A, and HIMA-8 to assess their impact on tropical cyclone (TC) PABUK from 1 to 4 January 2019. The findings demonstrate that the assimilation of three sets of AMVs diminishes the average initial position error and track forecast error after 42 h when compared to the control experiment. Nevertheless, none of the experiments’ analyses or forecasts of the TC intensity showed a statistically significant development. The findings for FY-2G and FY-4A AMVs may offer a direction forward for the FY AMVs series dataset for future implementation in the global data assimilation system of NWP models, similar to HIMA-8 AMVs, which shows a favourable performance in assimilating AMVs from assorted satellites for SEA forecasts.
Hyperspectral Remote Sensing Inversion and Monitoring of Organic Matter in Black Soil Based on Dynamic Fitness Inertia Weight Particle Swarm Optimization Neural Network
Authors: Chang Ruichun , Chen Zhe , Wang Daming , Guo Ke
Published: September 2022

Long-term degradation of black soil has led to reductions in soil fertility and ecological service functions, which have seriously threatened national food security and regional ecological security. This study is motivated by the UN’s Sustainable Development Goal (SDG) 2—Zero Hunger, specifically, SDG 2.4 Sustainable Food Production Systems. The aim was to monitor the soil organic matter (SOM) content of black soil and its dynamics via hyperspectral remote sensing inversion. This is of great significance to the effective utilization and sustainable development of black soil resources. Taking the typical black soil area of Northeast China as an example, the hyperspectral data of ground features were compared with SOM contents measured in soil samples to correlate SOM with spectral features. Based on their quantitative relationship, a dynamic fitness inertia weighted particle swarm optimization (DPSO) algorithm is proposed, which balances the global and local search abilities of a particle swarm optimization algorithm. The DPSO algorithm is applied to the parameter adjustment of an artificial neural network (BPNN), which is used instead of a traditional error back propagation algorithm, to build a DPSO-BPNN model. Then a global optimal analytical expression of hyperspectral inversion is obtained to improve the generalization ability and stability of the remote sensing quantitative inversion model. The results show that DPSO-BPNN model is more stable and accurate than existing models, such as multiple stepwise regression, partial least squares, and BP neural network models (adjust complex coefficient of determination = 0.89, root mean square error = 1.58, relative recent deviation = 2.93). The results of DPSO-BPNN inversion are basically consistent with the trend in SOM contents measured during surface geochemical exploration. As such, this study provides a basis for hyperspectral remote sensing inversion and monitoring of the SOM contents in black soil.
Stacking of Canopy Spectral Reflectance from Multiple Growth Stages Improves Grain Yield Prediction under Full and Limited Irrigation in Wheat
Authors: Hassan Muhammad Adeel , Fei Shuaipeng , Li Lei , Jin Yirong , Liu Peng , Rasheed Awais , Shawai Rabiu Sani , Zhang Liang , Ma Aimin , Xiao Yonggui , He Zhonghu
Published: September 2022

Grain yield (GY) prediction for wheat based on canopy spectral reflectance can improve selection efficiency in breeding programs. Time-series spectral information from different growth stages such as flowering to maturity is considered to have high accuracy in predicting GY and combining this information from multiple growth stages could effectively improve prediction accuracy. For this, 207 wheat cultivars and breeding lines were grown in full and limited irrigation treatments, and their canopy spectral reflectance was measured at the flowering, early, middle, and late grain fill stages. The potential of temporal spectral information at multiple growth stages for GY prediction was evaluated by a new method based on stacking the multiple growth stages data. Twenty VIs derived from spectral reflectance were used as the input feature of a support vector regression (SVR) to predict GY at each growth stage. The predicted GY values at multiple growth stages were trained by multiple linear regression (MLR) to establish a second-level prediction model. Results suggested that the prediction accuracy (R2) of VIs data from single growth stages ranged from 0.60 to 0.66 and 0.35 to 0.42 in the full and limited irrigation treatments, respectively. The prediction accuracy was increased by an average of 0.06, 0.07, and 0.07 after stacking the VIs of two, three, and four growth stages, respectively, under full irrigation. Similarly, under limited irrigation, the prediction accuracy was increased by 0.03, 0.04, and 0.04 by stacking the VIs of two, three, and four growth stages, respectively. Stacking of VIs of multiple important growth stages can increase the accuracy of GY prediction and application of a stable stacking model could increase the usefulness of data obtained from different phenotyping platforms.
Joint Satellite-Transmitter and Ground-Receiver Digital Pre-Distortion for Active Phased Arrays in LEO Satellite Communications
Authors: Chen Qingyue , Wang Zhugang , Pedersen Gert Frølund , Shen Ming
Published: September 2022

A novel joint satellite-transmitter and ground-receiver (JSG) digital pre-distortion (DPD) (JSG-DPD) technique is proposed to improve the linearity and power efficiency of the space-borne active phased arrays (APAs) in low Earth orbit (LEO) satellite communications. Different from the conventional DPD technique that requires a complex RF feedback loop, the DPD coefficients based on a generalized memory polynomial (GMP) model are extracted at the ground-receiver and then transmitted to the digital baseband front-end of the LEO satellite-transmitter via a satellite–ground bi-directional transmission link. The issue of the additive white Gaussian noise (AWGN) of the satellite–ground channel affecting the extraction of DPD coefficients is tackled using a superimposing training sequences (STS) method. The proposed technique has been experimentally verified using a 28 GHz phased array. The performance improvements in terms of error vector amplitude (EVM) and adjacent channel power ratio (ACPR) are 7.5% and 3.6 dB, respectively. Requiring limited space-borne resources, this technique offers a promising solution to achieve APA DPD for LEO satellite communications.