bluuebunny/crossref_metadata_2025 huggingface dataset:
Elastic and Dynamic Heterogeneity in Aging Alginate Gels
Authors: Pastore Raffaele , Siviello Ciro , Larobina Domenico
Published: October 2021

Anomalous aging in soft glassy materials has generated a great deal of interest because of some intriguing features of the underlying relaxation process, including the emergence of “ultra-long-range” dynamical correlations. An intriguing possibility is that such a huge correlation length is reflected in detectable ensemble fluctuations of the macroscopic material properties. We tackle this issue by performing replicated mechanical and dynamic light scattering (DLS) experiments on alginate gels, which recently emerged as a good model-system of anomalous aging. Here we show that some of the monitored quantities display wide variability, including large fluctuations in the stress relaxation and the occasional presence of two-step decay in the DLS decorrelation functions. By quantifying elastic fluctuation through the standard deviation of the elastic modulus and dynamic heterogeneities through the dynamic susceptibility, we find that both quantities do increase with the gel age over a comparable range. Our results suggest that large elastic fluctuations are closely related to ultra-long-range dynamical correlation, and therefore may be a general feature of anomalous aging in gels.
Physical, Mechanical, and Morphological Properties of Treated Sugar Palm/Glass Reinforced Poly(Lactic Acid) Hybrid Composites
Authors: Sherwani S. F. K. , Zainudin E. S. , Sapuan S. M. , Leman Z. , Khalina A.
Published: October 2021

This research was performed to evaluate the physical, mechanical, and morphological properties of treated sugar palm fiber (SPF)/glass fiber (GF) reinforced poly(lactic acid) (PLA) hybrid composites. Morphological investigations of tensile and flexural fractured samples of composites were conducted with the help of scanning electron microscopy (SEM). Alkaline and benzoyl chloride (BC) treatments of SPFs were performed. A constant weight fraction of 30% total fiber loading and 70% poly(lactic acid) were considered. The composites were initially prepared by a Brabender Plastograph, followed by a hot-pressing machine. The results reported that the best tensile and flexural strengths of 26.3 MPa and 27.3 MPa were recorded after alkaline treatment of SPF, while the highest values of tensile and flexural moduli of 607 MPa and 1847 MPa were recorded after BC treatment of SPF for SPF/GF/PLA hybrid composites. The novel SPF/GF/PLA hybrid composites could be suitable for fabricating automotive components.
Using Geopolymer Technology on Synthesizing Leucite Ceramics
Authors: Hsieh Yi-Che , Lee Wei-Hao , Liao Pin-Hsun
Published: October 2021

The aim of this study is to assess the process of synthesizing potassium-based geopolymers (KGL) into leucite ceramics with regard to five variables, namely, alkaline solution ratio (R), sintering time (S), calcining temperature (T), mixing time (M), and curing time (C). Under these conditions, the specimens were tested by the viscosity test, the mechanical properties test, X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) to understand the geopolymerization reactions and the characteristics of the KGL network. The results indicate that a KOH to K2O/SiO2 ratio of 1:1 promotes the reaction within metakaolin. XRD analysis of the KGL shows that, when the temperature is 1100 °C, the phase transforms into the leucite phase. Moreover, XRD analysis, mechanical properties, and FTIR all indicate improved characteristics when the curing time increases from 1 to 8 h. This might be attributed to the enhancement of the strong interaction between the matrix and the alkaline solution upon achieving adequate time to complete the geopolymerization process and forming a more stable three-dimensional structure. The formulation which formed the purest leucite phase consisted of: a 1:1 alkaline solution ratio, 10 min mixing time, 8 h curing time, 1200 °C calcining temperature, and 2 h sintering time.
An Engineered Specificity of Anti-Neoplastic Agent Loaded Magnetic Nanoparticles for the Treatment of Breast Cancer
Authors: Nair Anroop B. , Telsang Mallikarjun , Osmani Riyaz Ali
Published: October 2021

Nanoparticles have gained increased attention due to the prospection of drug delivery at target sites, thus limiting the systemic effects of the drugs. Their efficiency was further improved by adding special carriers such as magnetite (Fe3O4). It is one of the extensively used oxides of iron for both pharmaceutical and biomedical applications owing to its ease of preparation and biocompatibility. In this work, Gemcitabine magnetic nanoparticles were prepared using Fe3O4 and chitosan as the primary ingredients. Optimization was accomplished by Box–Behnken Design and factor interactions were evaluated. The desirability function approach was made to enhance the formulation concerning particle size, polydispersity index, and zeta potential. Based on this, optimized magnetic nanoparticles (O-MNP) were formulated with 300 mg of Fe3O4, 297.7 mg of chitosan, and a sonication time of 2.4 h, which can achieve the prerequisites of the target formulation. All other in vitro parameters were found to be following the requirement. In vitro cytotoxic studies for O-MNP were performed using cell cultures of breast cancer (MCF-7), leukemia (THP-1), prostate cancer (PC-3), and lung cancer (A549). O-MNP showed maximum inhibition growth with MCF-7 cell lines rather than other cell lines. The data observed here demonstrates the potential of magnetic nanoparticles of gemcitabine in treating breast cancers.
An Efficient Method of Calculating the Force and Torque in the Upsetting of Cylinders with Rotating Dies
Authors: Alexandrov Sergei , Lyamina Elena , Hwang Yeong-Maw
Published: October 2021

The process of upsetting, with rotating dies, is used to reduce the force required to deform the workpiece and to receive more homogeneous deformation compared to the same process without the rotational motion of the dies. The upper bound method is an efficient tool for a quick estimate of process parameters. The accuracy of upper bound solutions depends on the chosen class of kinematically admissible velocity fields. The present paper provides an efficient method for choosing kinematically admissible velocity fields that satisfy some stress boundary conditions if the associated flow rule is considered. The method applies to the upsetting of cylinders. It is expected that it leads to accurate solutions if friction is high enough. Besides, the kinematically admissible velocity field accounts for a rigid region near the axis of symmetry. Such a region inevitably occurs in exact solutions because the friction stress must vanish at the axis of symmetry. The final expression for the upper bound, on a combination of the force and torque, involves two arbitrary parameters. These parameters are determined using the upper bound theorem. An example is provided to illustrate the method.
DEM–FEM Coupling Simulation of the Transfer Chute Wear with the Dynamic Calibration DEM Parameters
Authors: Ye Fangping , Qiang Yuezhang , Jiang Weijie , Fu Xiang
Published: October 2021

Transfer chutes for bulk material conveying systems have significant importance in ship loading and unloading and are ‘worn’ from large mass flow and fast granular material flow conditions. In this investigation, the impact forces of different granular materials on the transfer chute wear process are considered; the DEM–FEM (Discrete Element Method–Finite Element Method) coupling method was used to calculate the wear and the deformation of the transfer chute. The stress–strain and cumulative contact energy from three different granular materials were analyzed under different working conditions. The results show that the wear, stress–strain, and cumulative contact energy of the transfer chute are closely related to the belt speed, the chute inclination angle, and the types of granular materials; the impact force and the stress–strain on the transfer chute achieves maximum value under a 4 m/s belt speed condition; meanwhile, with the increase of belt speed by 0.5 m/s, the wear of the transfer chute increases 25% and the deformation increases 20%; the shape variable, wear area, and normal cumulative contact capacity of the transfer chute are the smallest with a transfer chute inclination angle from 40° to 45°.
Development of a Quantitative Method for Analysis of Compounds Found in Mondia whitei Using HPLC-DAD
Authors: Chokwe Ramakwala Christinah , Dube Simiso , Nindi Mathew Muzi
Published: October 2021

Mondia whitei is one of the popular medicinal plants in Africa, which has been used extensively across the continent to cure various ailments. Products prepared from this plant are distributed commercially. In this study, an HPLC-DAD method was developed and validated for seven compounds to enable quality control of these products. The method was validated using the external standard-calibration and the standard-addition methods which were found not significantly different. The method was found to be linear in the ranges 1–14 mg/L and 3–14 mg/kg with correlation coefficients from 0.9942–0.9995 and 0.9907–0.9993 in the solvent and the different matrices, respectively. The limit of detection (LOD) values of the method were found to range between 0.1–1.2 mg/L in the solvent and syrup, and between 0.4–1.2 mg/kg in the teabag and root powder. The limit of quantification (LOQ) values were found to range between 0.5–3.9 mg/L in the solvent and syrup, and between 1.4–3.8 mg/kg in the teabag and root powder. The method was also found to be precise with percentage relative standard deviations below 5% and 10% in the solvent and matrices, respectively. The method was applied to Mondia whitei products for qualitative and quantitative analysis.
Upgrading of Wash Oil through Reduction of Nitrogen-Containing Compounds
Authors: Kim Su Jin
Published: October 2021

As part of improving the quality of wash oil, the reduction of three kinds of nitrogen-containing compounds (NCs), including quinoline (QU), iso-quinoline (IQU), and indole (IN), found in wash oil was examined by liquid–liquid equilibrium extraction. The wash oil and an aqueous solution of formamide were used as the raw material and the solvent, respectively. Increasing the volume fraction of water in the solvent in the initial state (yw,0) resulted in a decrease in the distribution coefficients of each NC, while inversely, the selectivity of each NC in reference to 2-methylnaphthalene increased. The selectivity ranges of QU, IQU and IN at yw,0 = 0.05~0.3 were 19~57, 19~56 and 50~79, respectively. Through five stages of equilibrium extraction performed under the condition of yw,0 = 0.05, the concentrations of QU and IQU contained in the raffinate oil recovered at the fifth stage were reduced by about 69% and 65% compared to those contained in the wash oil. The concentration of IN in particular, a useful compound in the chemical industry, which is a raw material for pharmaceuticals, dyes, and fragrances, was reduced by 93.4% through a five-stage extraction operation. The formamide extraction method of this study was highly efficient in reducing the NC present in the wash oil, showing the feasibility of this method.
Intellectual Capital: A Review and Bibliometric Analysis
Authors: Quintero-Quintero Wilder , Blanco-Ariza Ana Beatriz , Garzón-Castrillón Manuel Alfonso
Published: October 2021

Intellectual capital is managed by competencies and the development of information and communication technologies, which have seen high growth and impact in higher education institutions related to scientific publications. The main objective of this study was to provide a summary of the general review of studies related to intellectual capital around the world. Methodology: the Bibliometric analysis was carried out using the Bibliometrix library and BiblioShiny platform of the RStudio® software through the data obtained from the Scopus database. Findings: in total, 389 documents in the Scopus database used “capital”, “intellectual”, “research” and “institutions” as keywords with a growth rate of 2.34% every year from 1947 to 2021. The publications were written by around 866 authors, mainly from the USA, the UK, and Spain. Original value: the data obtained show that intellectual capital has been important and relevant in the scientific publications of the last six years, which were related by the number of authors by institutions.
Differences in Citation Patterns across Areas, Article Types and Age Groups of Researchers
Authors: Mendoza Marcelo
Published: October 2021

The evaluation of research proposals and academic careers is subject to indicators of scientific productivity. Citations are critical signs of impact for researchers, and many indicators are based on these data. The literature shows that there are differences in citation patterns between areas. The scope and depth that these differences may have to motivate the extension of these studies considering types of articles and age groups of researchers. In this work, we conducted an exploratory study to elucidate what evidence there is about the existence of these differences in citation patterns. To perform this study, we collected historical data from Scopus. Analyzing these data, we evaluate if there are measurable differences in citation patterns. This study shows that there are evident differences in citation patterns between areas, types of publications, and age groups of researchers that may be relevant when carrying out researchers’ academic evaluation.
Recent Progress in the Development of a-Se/CMOS Sensors for X-ray Detection
Authors: Hellier Kaitlin , Benard Emmie , Scott Christopher C. , Karim Karim S. , Abbaszadeh Shiva
Published: October 2021

Amorphous selenium (a-Se) is a glass-former capable of deposition at high rates by thermal evaporation over a large area. It was chosen as a direct conversion material due to its appealing properties for imaging in both low and high X-ray energy ranges (<30 keV and <30 keV, respectively). It has a bandgap of 2.2 eV and can achieve high photodetection efficiency at short wavelengths less than 400 nm which makes it appealing for indirect conversion detectors. The integration of a-Se with readout integrated circuits started with thin-film transistors for digital flat panel X-ray detectors. With increasing applications in life science, biomedical imaging, X-ray imaging, high energy physics, and industrial imaging that require high spatial resolution, the integration of a-Se and CMOS is one direct way to improve the high-contrast visualization and high-frequency response. Over the past decade, significant improvements in a-Se/CMOS technologies have been achieved with improvements to modulation transfer function and detective quantum efficiency. We summarize recent advances in integrating and photon-counting detectors based on a-Se coupled with CMOS readout and discuss some of the shortcomings in the detector structure, such as low charge conversion efficiency at low electric field and high dark current at high electric field. Different pixel architectures and their performance will be highlighted.
The Significance of ‘the Person’ in Addiction
Authors: Hurley Pádraic Mark
Published: October 2021

Van Gordon et al. outline the classification of their Ontological Addiction Theory (OAT), including its aetiology and treatment. In this review article I will from an appreciative perspective question some of its fundamental assumptions by presenting an alternative view on the ontology of ‘the person’, as distinct from its presently assumed conventional conflation with a contracted separate egoic self. I will propose this view as structurally and ethically significant for the ‘embodied’ experience of a reconstructed “dynamic and non-dual self”, as cultivated in their treatment. Rather than this reconstructed self simply being socially desirable for functional purposes, I will underscore the meaning-generative case for ontological status, in the absence of which, a pervasive ‘sense of lack’ is evident, with all attendant individual, psychological, social, ecological and ethical implications. This article brings a developmental psychology perspective to bear in appreciating ‘personhood’ as an emergent, progressively realised and is thus similarly aligned with the intent of OAT in overcoming egoic addictive suffering. This mapping of the territory however populates a blind spot in OAT’s diagnosis by affirming unique personhood, a quality of ‘integrative presence’, meaningfully understood as a psycho-spiritual ontological reality. It offers, as with OAT’s stated intent, the merit of avoiding attendant mental health and developmental pitfalls, which can beset what we may discern as an implicit transcendental reductionist assumption operative in OAT, where ‘the many’ are reduced to ‘the One’ and there are, it is assumed, no real many. This framing is resonant with the lived experience of healthy ‘individuation’, a process distinct from the problematic phenomenon of ‘individualism’, evidenced by the empirical data on post-conventional human development, which potentially provides diagnostic markers for any optimal treatment discernment. It is also attuned to what many recognise as a contemporary Fourth Turning in Buddhism, in its conscious evolutionary recognition of the emergence in non-dual states of a ‘unique personal perspective’, and/or a relative individuation within the whole. This differentiation has formerly been interpreted through an ‘impersonal’ lens as an egoic holdover, and potentially inhibits ethical action in the world, as distinct from the ethical import and potential fruits stemming from the ontological affirmation of the person.
The Kojiki/Nihon Shoki Mythology and Chinese Mythology: Theme, Structure, and Meaning
Authors: Tu Xiaofei , Xie Wendy
Published: October 2021

This essay will compare myths found in the Kojiki and the Nihon Shoki with thematically and structurally similar Chinese myths, and other Japanese texts, in order to shed light on the meanings of both Japanese and Chinese mythology. The authors’ approach is partly in the critical textual study tradition that traces back to Gu Jiegang and Tsuda Sokichi, and partly informed by comparative mythologists, such as Matsumae Takeshi, Nelly Naumann, and Antonio Klaus, with attention to Proppian and Levi-Straussian motifs in structural studies. First, we shall discuss some common themes in Chinese and Kojiki/Nihon Shoki myths. Second, we shall point out common structures in both Chinese and Japanese myths. Finally, we shall try to show how such common themes and structures could potentially help us understand the meanings of the myths in discussion.
Secularization, Modernity, and Belief Shaping: Night School and Livelihood Education at the Chinese YMCA in the Early Twentieth Century
Authors: Yang Yi , Liu Xunqian , Ko Kuan-Yu
Published: October 2021

In the early 20th century, influenced by evangelicals in the United States, the Young Men’s Christian Association (YMCA) launched the “Four Movements” in response to the “Four Maladies” of Chinese society. Among the four movements, “livelihood education” is used to help raise productivity and save people from poverty. Research on the YMCA in modern China rarely focuses on livelihood education, and even when it does, it does not focus on educated adult civilians or explore how the YMCA has changed the course of their lives. Based on fieldwork and detailed analysis of historical documents, this paper traces the formation of three night schools that have adopted various forms of “Christianized” and “secularization” practices and sheds light on the lives of two typical students whose experiences in YMCA night school were still less known. This study will demonstrate and analyze the role of livelihood education in introducing Western civilization and Christian ideas to China’s labor class. YMCA night schools not only helped ordinary Chinese working people acquire basic livelihood skills on a secular level, which enables them to enter a higher class in society and exert influence, but also reshaped their beliefs.
Slippery Entanglements: Spiritual and Gendered Experiences of Uncertainty in the Riverine Context of Bengali Char lands
Authors: Prins Annemiek
Published: October 2021

This paper focuses on the spiritual and gendered experiences of dwelling-in-uncertainty in the context of Bengali char lands. Chars are temporary sandbanks in the river that continuously erode and re-emerge as the river changes course, thereby subjecting their inhabitants to repetitious cycles of losing and regaining land. In this paper I take the ethnographic literature on Bengali chars as a point of departure for exploring what the radical uncertainty of climate change might mean in a context where erosion or land loss does not necessarily involve the irreversible loss of a particular habitat, but often coincides with the anticipation of return. In analyzing the gendered ways in which char dwellers navigate this spiraling cycle of land loss and return, I draw specific attention to the churning, immaterial and spiritual powers that reside below and beyond the water, thereby highlighting the ways in which people are caught up in a land/waterscape that is only knowable to some extent. Whereas debates around climate change often treat religion and spirituality as either obstacles to knowledge or vehicles of meaningful storytelling, this paper deliberately foregrounds the more-than-human forces that linger at the periphery of people’s perception and knowledge of the world. In doing so, the paper seeks to move beyond probabilistic notions of climate change and adaptation towards a diverse understanding of the existential uncertainties of the Anthropocene.
Cyber Risk Quantification: Investigating the Role of Cyber Value at Risk
Authors: Orlando Albina
Published: October 2021

The aim of this paper is to deepen the application of value at risk in the cyber domain, with particular attention to its potential role in security investment valuation. Cyber risk is a fundamental component of the overall risk faced by any organization. In order to plan the size of security investments and to estimate the consequent risk reduction, managers strongly need to quantify it. Accordingly, they can decide about the possibility of sharing residual risk with a third party, such as an insurance company. Recently, cyber risk management techniques are including some risk quantile-based measures that are widely employed in the financial domain. They refer to value at risk that, in the cyber context, takes the name of cyber value at risk (Cy-VaR). In this paper, the main features and challenging issues of Cy-VaR are examined. The possible use of this risk measure in supporting investment decisions in cyber context is discussed, and new risk-based security metrics are proposed. Some simple examples are given to show their potential.
Improved Calibration of Wind Estimates from Advanced Scatterometer MetOp-B in Korean Seas Using Deep Neural Network
Authors: Park Sung-Hwan , Yoo Jeseon , Son Donghwi , Kim Jinah , Jung Hyung-Sup
Published: October 2021

Satellite-based observations of sea wind are useful for forecasting marine weather and performing marine disaster management. Meteorological Operational Satellite-B (MetOp-B) is one of the satellites that provide wind products through a scatterometer named the Advanced Scatterometer (ASCAT). Since the linear regression method has been conventionally employed for calibrating remotely-sensed wind data, deviations and biases remain un-resolved to some degree. For coastal applications, these remotely-sensed wind data need to be calibrated again using local in-situ measurements in order to provide more accurate and realistic information. Thus, this study proposed a new method to calibrate ASCAT-based wind speed estimates using artificial neural networks. Herein, a deep neural network (DNN) model was applied. Wind databases collected during a period from 2012 to 2019 by the MetOp-B ASCAT and ten buoy stations in Korean seas were considered for deep learning-based calibration. ASCAT-based wind data and in-situ measurements were collocated in space and time. They were then separated into training and validation sets. A DNN model was designed and trained using multiple input variables such as observation location, sensing date and time, wind speed, and wind direction of the training set. The DNN-based best fit calibration model was evaluated using the validation set. The mean of biases between ASCAT-based and in-situ wind speeds was found to be decreased from 0.41 to 0.05 m/s on average for all buoy locations. The root mean squared error (RMSE) of wind speed was reduced from 1.38 m/s to 0.93 m/s. Moreover, the DNN-based calibration considerably improved the quality of wind speeds of less than 4 m/s, and of high wind speeds of 11–25 m/s. These results suggest that ASCAT-based observations can accurately represent real wind fields if a DNN-based calibration approach is applied.
A Robust Adaptive Unscented Kalman Filter for Floating Doppler Wind-LiDAR Motion Correction
Authors: Salcedo-Bosch Andreu , Rocadenbosch Francesc , Sospedra Joaquim
Published: October 2021

This study presents a new method for correcting the six degrees of freedom motion-induced error in ZephIR 300 floating Doppler Wind-LiDAR-derived data, based on a Robust Adaptive Unscented Kalman Filter. The filter takes advantage of the known floating Doppler Wind-LiDAR (FDWL) dynamics, a velocity–azimuth display algorithm, and a wind model describing the LiDAR-retrieved wind vector without motion influence. The filter estimates the corrected wind vector by adapting itself to different atmospheric and motion scenarios, and by estimating the covariance matrices of related noise processes. The measured turbulence intensity by the FDWL (with and without correction) was compared against a reference fixed LiDAR over a 25-day period at “El Pont del Petroli”, Barcelona. After correction, the apparent motion-induced turbulence was greatly reduced, and the statistical indicators showed overall improvement. Thus, the Mean Difference improved from −1.70% (uncorrected) to 0.36% (corrected), the Root Mean Square Error (RMSE) improved from 2.01% to 0.86%, and coefficient of determination improved from 0.85 to 0.93.
Estimation of Plot-Level Burn Severity Using Terrestrial Laser Scanning
Authors: Gallagher Michael R. , Maxwell Aaron E. , Guillén Luis Andrés , Everland Alexis , Loudermilk E. Louise , Skowronski Nicholas S.
Published: October 2021

Monitoring wildland fire burn severity is important for assessing ecological outcomes of fire and their spatial patterning as well as guiding efforts to mitigate or restore areas where ecological outcomes are negative. Burn severity mapping products are typically created using satellite reflectance data but must be calibrated to field data to derive meaning. The composite burn index (CBI) is the most widely used field-based method used to calibrate satellite-based burn severity data but important limitations of this approach have yet to be resolved. The objective of this study was focused on predicting CBI from point cloud and visible-spectrum camera (RGB) metrics derived from single-scan terrestrial laser scanning (TLS) datasets to determine the viability of TLS data as an alternative approach to estimating burn severity in the field. In our approach, we considered the predictive potential of post-scan-only metrics, differenced pre- and post-scan metrics, RGB metrics, and all three together to predict CBI and evaluated these with candidate algorithms (i.e., linear model, random forest (RF), and support vector machines (SVM) and two evaluation criteria (R-squared and root mean square error (RMSE)). In congruence with the strata-based observations used to calculate CBI, we evaluated the potential approaches at the strata level and at the plot level using 70 TLS and 10 RGB independent variables that we generated from the field data. Machine learning algorithms successfully predicted total plot CBI and strata-specific CBI; however, the accuracy of predictions varied among strata by algorithm. RGB variables improved predictions when used in conjunction with TLS variables, but alone proved a poor predictor of burn severity below the canopy. Although our study was to predict CBI, our results highlight that TLS-based methods for quantifying burn severity can be an improvement over CBI in many ways because TLS is repeatable, quantitative, faster, requires less field-expertise, and is more flexible to phenological variation and biomass change in the understory where prescribed fire effects are most pronounced. We also point out that TLS data can also be leveraged to inform other monitoring needs beyond those specific to wildland fire, representing additional efficiency in using this approach.
A Training Sample Migration Method for Wetland Mapping and Monitoring Using Sentinel Data in Google Earth Engine
Authors: Fekri Erfan , Latifi Hooman , Amani Meisam , Zobeidinezhad Abdolkarim
Published: October 2021

Wetlands are one of the most important ecosystems due to their critical services to both humans and the environment. Therefore, wetland mapping and monitoring are essential for their conservation. In this regard, remote sensing offers efficient solutions due to the availability of cost-efficient archived images over different spatial scales. However, a lack of sufficient consistent training samples at different times is a significant limitation of multi-temporal wetland monitoring. In this study, a new training sample migration method was developed to identify unchanged training samples to be used in wetland classification and change analyses over the International Shadegan Wetland (ISW) areas of southwestern Iran. To this end, we first produced the wetland map of a reference year (2020), for which we had training samples, by combining Sentinel-1 and Sentinel-2 images and the Random Forest (RF) classifier in Google Earth Engine (GEE). The Overall Accuracy (OA) and Kappa coefficient (KC) of this reference map were 97.93% and 0.97, respectively. Then, an automatic change detection method was developed to migrate unchanged training samples from the reference year to the target years of 2018, 2019, and 2021. Within the proposed method, three indices of the Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), and the mean Standard Deviation (SD) of the spectral bands, along with two similarity measures of the Euclidean Distance (ED) and Spectral Angle Distance (SAD), were computed for each pair of reference–target years. The optimum threshold for unchanged samples was also derived using a histogram thresholding approach, which led to selecting the samples that were most likely unchanged based on the highest OA and KC for classifying the test dataset. The proposed migration sample method resulted in high OAs of 95.89%, 96.83%, and 97.06% and KCs of 0.95, 0.96, and 0.96 for the target years of 2018, 2019, and 2021, respectively. Finally, the migrated samples were used to generate the wetland map for the target years. Overall, our proposed method showed high potential for wetland mapping and monitoring when no training samples existed for a target year.
Quantification of Natural and Anthropogenic Driving Forces of Vegetation Changes in the Three-River Headwater Region during 1982–2015 Based on Geographical Detector Model
Authors: Gao Siqi , Dong Guotao , Jiang Xiaohui , Nie Tong , Yin Huijuan , Guo Xinwei
Published: October 2021

The three-river headwater region (TRHR) supplies the Yangtze, Yellow, and Lantsang rivers, and its ecological environment is fragile, hence it is important to study the surface vegetation cover status of the TRHR to facilitate its ecological conservation. The normalized difference vegetation index (NDVI) can reflect the cover status of surface vegetation. The aims of this study are to quantify the spatial heterogeneity of the NDVI, identify the main driving factors influencing the NDVI, and explore the interaction between these factors. To this end, we used the global inventory modeling and mapping studies (GIMMS)-NDVI data from the TRHR from 1982 to 2015 and included eight natural factors (namely slope, aspect, elevation, soil type, vegetation type, landform type, annual mean temperature, and annual precipitation) and three anthropogenic factors (gross domestic product (GDP), population density, and land use type), which we subjected to linear regression analysis, the Mann-Kendall statistical test, and moving t-test to analyze the spatial and temporal variability of the NDVI in the TRHR over 34 years, using a geographical detector model. Our results showed that the NDVI distribution of the TRHR was high in the southeast and low in the northwest. The change pattern exhibited an increasing trend in the west and north and a decreasing trend in the center and south; overall, the mean NDVI value from 1982 to 2015 has increased. Annual precipitation was the most important factor influencing the NDVI changes in the TRHR, and factors, such as annual mean temperature, vegetation type, and elevation, also explained the vegetation coverage status well. The influence of natural factors was generally stronger than that of anthropogenic factors. The NDVI factors had a synergistic effect, exhibiting mutual enhancement and nonlinear enhancement relationships. The results of this study provide insights into the ecological conservation of the TRHR and the ecological security and development of the middle and lower reaches.
Creating and Testing Explainer Videos for Earth Observation
Authors: Hodam Henryk , Rienow Andreas , Juergens Carsten
Published: October 2021

Learning videos can be concise learning packages that offer a wide range of possibilities when it comes to present topics in an up-to-date way and disseminating them in a variety of learning environments. Videos are already a primary source of information in our society; however, few examples convey earth observation topics. Over recent decades, numerous studies established guidelines on how educational videos can be successful. This paper presents a workflow to use these guidelines in the creation of learning videos covering the basic concepts of earth observation. The target groups for these videos are secondary students as well as anyone interested in learning about earth observation. Two of those videos, one on earth observation in general and one on the basics of the electromagnetic spectrum, were used in this research. To test whether or not the workflow leads to effective learning videos and to compare them to traditional text and illustration material derived from those videos, a pre-test/post-test study was undertaken focusing on German pupils in their final year at secondary school as well as first semester university students. Due to the special circumstances faced during the COVID-19 crisis, this experimental setup used a combination of online questionnaire tools and a web environment. The results show that both methods were effective resources that led to a significant increase in knowledge—raising the test results by 21% for the video and 13% for the text and illustration group.
Multi-Scale Feature Mapping Network for Hyperspectral Image Super-Resolution
Authors: Zhang Jing , Shao Minhao , Wan Zekang , Li Yunsong
Published: October 2021

Hyperspectral Image (HSI) can continuously cover tens or even hundreds of spectral segments for each spatial pixel. Limited by the cost and commercialization requirements of remote sensing satellites, HSIs often lose a lot of information due to insufficient image spatial resolution. For the high-dimensional nature of HSIs and the correlation between the spectra, the existing Super-Resolution (SR) methods for HSIs have the problems of excessive parameter amount and insufficient information complementarity between the spectra. This paper proposes a Multi-Scale Feature Mapping Network (MSFMNet) based on the cascaded residual learning to adaptively learn the prior information of HSIs. MSFMNet simplifies each part of the network into a few simple yet effective network modules. To learn the spatial-spectral characteristics among different spectral segments, a multi-scale feature generation and fusion Multi-Scale Feature Mapping Block (MSFMB) based on wavelet transform and spatial attention mechanism is designed in MSFMNet to learn the spectral features between different spectral segments. To effectively improve the multiplexing rate of multi-level spectral features, a Multi-Level Feature Fusion Block (MLFFB) is designed to fuse the multi-level spectral features. In the image reconstruction stage, an optimized sub-pixel convolution module is used for the up-sampling of different spectral segments. Through a large number of verifications on the three general hyperspectral datasets, the superiority of this method compared with the existing hyperspectral SR methods is proved. In subjective and objective experiments, its experimental performance is better than its competitors.
Hybrid MSRM-Based Deep Learning and Multitemporal Sentinel 2-Based Machine Learning Algorithm Detects Near 10k Archaeological Tumuli in North-Western Iberia
Authors: Berganzo-Besga Iban , Orengo Hector A. , Lumbreras Felipe , Carrero-Pazos Miguel , Fonte João , Vilas-Estévez Benito
Published: October 2021

This paper presents an algorithm for large-scale automatic detection of burial mounds, one of the most common types of archaeological sites globally, using LiDAR and multispectral satellite data. Although previous attempts were able to detect a good proportion of the known mounds in a given area, they still presented high numbers of false positives and low precision values. Our proposed approach combines random forest for soil classification using multitemporal multispectral Sentinel-2 data and a deep learning model using YOLOv3 on LiDAR data previously pre-processed using a multi–scale relief model. The resulting algorithm significantly improves previous attempts with a detection rate of 89.5%, an average precision of 66.75%, a recall value of 0.64 and a precision of 0.97, which allowed, with a small set of training data, the detection of 10,527 burial mounds over an area of near 30,000 km2, the largest in which such an approach has ever been applied. The open code and platforms employed to develop the algorithm allow this method to be applied anywhere LiDAR data or high-resolution digital terrain models are available.
An Overview of the Special Issue on Plant Phenotyping for Disease Detection
Authors: Pineda Mónica
Published: October 2021

According to the latest United Nations estimates in September 2021, the world’s population is now 7 [...]
Performance of Multi-GNSS Real-Time UTC(NTSC) Time and Frequency Transfer Service Using Carrier Phase Observations
Authors: Zhang Pengfei , Tu Rui , Lu Xiaochun , Fan Lihong , Zhang Rui
Published: October 2021

The technique of carrier phase (CP), based on the global navigation satellite system (GNSS), has proven to be a highly effective spatial tool in the field of time and frequency transfer with sub-nanosecond accuracy. The rapid development of real-time GNSS satellite orbit and clock determinations has enabled GNSS time and frequency transfer using the CP technique to be performed in real-time mode, without any issues associated with latency. In this contribution, we preliminarily built the prototype system of real-time multi-GNSS time and frequency transfer service in National Time Service Center (NTSC) of the Chinese Academy of Sciences (CAS), which undertakes the task to generate, maintains and transmits the national standard of time and frequency UTC(NTSC). The comprehensive assessment of the availability and quality of the service system were provided. First, we assessed the multi-GNSS state space representation (SSR) correction generated in real-time multi-GNSS prototype system by combining broadcast ephemeris through a comparison with the GeoForschungsZentrum (GFZ) final products. The statistical results showed that the orbit precision in three directions was smaller than 6 cm for global positioning system (GPS) and smaller than approximately 10 cm for BeiDou satellite system (BDS). The root mean square (RMS) values of clock differences for GPS were approximately 2.74 and 6.74 ns for the GEO constellation of BDS, 3.24 ns for IGSO, and 1.39 ns for MEO. The addition, the GLObal NAvigation Satellite System (GLONASS) and Galileo satellite navigation system (Galileo) were 4.34 and 1.32 ns, respectively. In order to assess the performance of real-time multi-GNSS time and frequency transfer in a prototype system, the four real-time time transfer links, which used UTC(NTSC) as the reference, were employed to evaluate the performance by comparing with the solution determined using the GFZ final products. The RMS could reach sub-nanosecond accuracy in the two solutions, either in the SSR or GFZ solution, or in GPS, BDS, GLONASS, and Galileo. The frequency stability within 10,000 s was 3.52 × 10−12 for SSR and 3.47 × 10−12 for GFZ and GPS, 3.63 × 10−12 for SSR and 3.53 × 10−12 for GFZ for BDS, 3.57 × 10−12 for SSR and 3.52 × 10−12 for GFZ for GLONASS, and 3.56 × 10−12 for SSR and 3.48 × 10−12 for GFZ for Galileo.
A Method of Infrared Small Target Detection in Strong Wind Wave Backlight Conditions
Authors: Ma Dongdong , Dong Lili , Xu Wenhai
Published: October 2021

How to accurately detect small targets from the complex maritime environment has been a bottleneck problem. The strong wind-wave backlight conditions (SWWBC) is the most common situation in the process of distress target detection. In order to solve this problem, the main contribution of this paper is to propose a small target detection method suitable for SWWBC. First of all, for the purpose of suppressing the gray value of the background, it is analyzed that some minimum points with the lowest gray value tend to gather in the interior of the small target. As the distance from the extreme point increases, the gray value of the pixel in all directions also increases by the same extent. Therefore, an inverse Gaussian difference (IGD) preprocessing method similar to the distribution of the target pixel value is proposed to suppress the uniform sea wave and intensity of the sky background. So as to achieve the purpose of background suppression. Secondly, according to the feature that the small target tends to “ellipse shape” in both horizontal and vertical directions, a multi-scale and multi-directional Gabor filter is applied to filter out interference without “ellipse shape”. Combined with the inter-scale difference (IsD) operation and iterative normalization operator to process the results of the same direction under different scales, it can further suppress the noise interference, highlight the significance of the target, and fuse the processing results to enrich the target information. Then, according to different texture feature distributions of the target and noise in the multi-scale feature fusion results, a cross-correlation (CC) algorithm is proposed to eliminate noise. Finally, according to the dispersion of the number of extreme points and the significance of the intensity of the small target compared with the sea wave and sky noise, a new peak significance remeasurement method is proposed to highlight the intensity of the target and combined with a binary method to achieve accurate target segmentation. In order to better evaluate the performance index of the proposed method, compared with current state-of-art maritime target detection technologies. The experimental results of multiple image sequence sets confirm that the proposed method has higher accuracy, lower false alarm rate, lower complexity, and higher stability.
Evaluation of Reanalysis Datasets for Solar Radiation with In Situ Observations at a Location over the Gobi Region of Xinjiang, China
Authors: Wang Yu , Zhao Xueshang , Mamtimin Ali , Sayit Hajigul , Abulizi Simayi , Maturdi Amina , Yang Fan , Huo Wen , Zhou Chenglong , Yang Xinghua , Liu Xinchun
Published: October 2021

Solar radiation is the most important source of energy on the Earth. The Gobi area in the eastern Xinjiang region, due to its geographic location and climate characteristics, has abundant solar energy resources. In order to provide detailed scientific data supporting solar energy development in this area, we used ground-based data to evaluate the applicability of the five reanalysis data sources: the Clouds and the Earth’s Radiant Energy System (CERES), the European Center for Medium-Range Weather Forecasts Reanalysis version 5 (ERA5), the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA2), and the Japanese 55-year Reanalysis (JRA-55). Our results indicated that the CERES data show underestimated short-wave radiation and overestimated long-wave radiation. The correlation coefficients (r) between the ERA5 dataset and the net long-wave and short-wave radiation in observation were 0.92 and 0.91, respectively, and the r between the MERRA2 dataset and the net long-wave and short-wave radiation in observation were both 0.88. The JRA-55 dataset overestimated the long-wave radiation flux and underestimated the short-wave radiation flux. The clearness index (kt) of all datasets was poor during autumn and winter, the ERA5 estimates were cloudy when the actual condition was sunny, while the JRA-55 estimates were sunny when the actual condition was cloudy. Overall, the radiation flux in the ERA5 dataset had the highest applicability in the Gobi region.
Performance of BDS-2/3, GPS, and Galileo Time Transfer with Real-Time Single-Frequency Precise Point Positioning
Authors: Xiao Xia , Shen Fei , Lu Xiaochun , Shen Pengli , Ge Yulong
Published: October 2021

Single-frequency (SF) receivers are much cheaper than that of dual-frequency (DF). Even though DF precise point positioning (PPP) is nowadays applied in the time community, the cost of equipment is one of the key considerations for time users. Furthermore, the hardware delay calibration of single-frequency devices is simpler than that of dual-frequency devices. In addition, there is no literature to study real-time SF PPP time transfer. In this contribution, the possibility of time transfer using SF PPP was studied. The Un-combined SF PPP was employed for time transfer with ionospheric-constraint using real-time precise products. In this case, 18 multi-GNSS experiment (MGEX) stations and one time lab station were used to study real-time SF PPP time transfer using GPS, Galileo and BDS-2/3 satellites with 20-day. The results suggested that real-time single-frequency PPP can meet time transfer. the standard deviation (STD) of the clock difference obtained from GPS-only, Galileo-only and BDS-2/3 single-frequency PPP are about (0.51, 0.54, 0.91) ns, respectively. The frequency stability of real-time single-frequency PPP can achieve (1E-12, 1E-13, 1E-13) level at short-term and (1E-13, 1E-13, 1E-14) level at long-term, respectively, for BDS-2/3, Galileo-only and GPS-only based.