bluuebunny/crossref_metadata_2025 huggingface dataset:
Synergies of Human Umbilical Vein Endothelial Cell-Laden Calcium Silicate-Activated Gelatin Methacrylate for Accelerating 3D Human Dental Pulp Stem Cell Differentiation for Endodontic Regeneration
Authors: Lai Wei-Yun , Lee Tzu-Hsin , Chen Jian-Xun , Ng Hooi-Yee , Huang Tsui-Hsien , Shie Ming-You
Published: September 2021

According to the Centers for Disease Control and Prevention, tooth caries is a common problem affecting 9 out of every 10 adults worldwide. Dentin regeneration has since become one of the pressing issues in dentistry with tissue engineering emerging as a potential solution for enhancing dentin regeneration. In this study, we fabricated cell blocks with human dental pulp stem cells (hDPSCs)-laden alginate/fish gelatin hydrogels (Alg/FGel) at the center of the cell block and human umbilical vascular endothelial cells (HUVEC)-laden Si ion-infused fish gelatin methacrylate (FGelMa) at the periphery of the cell block. 1H NMR and FTIR results showed the successful fabrication of Alg/FGel and FGelMa. In addition, Si ions in the FGelMa were noted to be bonded via covalent bonds and the increased number of covalent bonds led to an increase in mechanical properties and improved degradation of FGelMa. The Si-containing FGelMa was able to release Si ions, which subsequently significantly not only enhanced the expressions of angiogenic-related protein, but also secreted some cytokines to regulate odontogenesis. Further immunofluorescence results indicated that the cell blocks allowed interactions between the HUVEC and hDPSCs, and taken together, were able to enhance odontogenic-related markers’ expression, such as alkaline phosphatase (ALP), dentin matrix phosphoprotein-1 (DMP-1), and osteocalcin (OC). Subsequent Alizarin Red S stain confirmed the benefits of our cell block and demonstrated that such a novel combination and modification of biomaterials can serve as a platform for future clinical applications and use in dentin regeneration.
The Synthesis, Characterization and Applications of Polyhydroxyalkanoates (PHAs) and PHA-Based Nanoparticles
Authors: Samrot Antony V. , Samanvitha Sree K. , Shobana N. , Renitta Emilin R. , Senthilkumar P. , Kumar Suresh S. , Abirami S. , Dhiva S. , Bavanilatha M. , Prakash P. , Saigeetha S. , Shree Krithika S. , Thirumurugan R.
Published: September 2021

Polyhydroxyalkanoates (PHAs) are storage granules found in bacteria that are essentially hydroxy fatty acid polyesters. PHA molecules appear in variety of structures, and amongst all types of PHAs, polyhydroxybutyrate (PHB) is used in versatile fields as it is a biodegradable, biocompatible, and ecologically safe thermoplastic. The unique physicochemical characteristics of these PHAs have made them applicable in nanotechnology, tissue engineering, and other biomedical applications. In this review, the optimization, extraction, and characterization of PHAs are described. Their production and application in nanotechnology are also portrayed in this review, and the precise and various production methods of PHA-based nanoparticles, such as emulsion solvent diffusion, nanoprecipitation, and dialysis are discussed. The characterization techniques such as UV-Vis, FTIR, SEM, Zeta Potential, and XRD are also elaborated.
Evaluations of Electrostatic Filtration Efficiency and Antibacterial Efficacy of Antibacterial Electret Polypropylene Filters: Effects of Using Low Molecular Antibacterial Agent as Additive
Authors: Lin Jia-Horng , Shih Ying-Huei , Huang Chen-Hung , Lai Mei-Feng , Lee Shu-An , Shiu Bing-Chiuan , Lou Ching-Wen
Published: September 2021

In recent years, air filtration has been gaining much attention, and now people are much more concerned about antibacterial filters due to the spreading of COVID-19. The electret polypropylene (PP) nonwoven fabrics possess excellent filtration efficiency but a limited antibacterial effect against S. aureus and E. coli, and therefore triclosan is used in this study. Serving as an antibacterial agent, triclosan with a low molecular weight is an effective additive for the test results, indicating that the presence of triclosan strengthens the antibacterial effects of the filters. In addition, triclosan also strengthens the PP’s crystallinity, which in turn betters the filtration efficiency of the filters concurrently. Demonstrating powerful filtration and antibacterial performances, the antibacterial electret PP filters are highly qualified for filter applications.
Optimization of Glass Transition Temperature and Pot Life of Epoxy Blends Using Response Surface Methodology (RSM)
Authors: Junid Ramli , Siregar Januar Parlaungan , Endot Nor Azam , Razak Jeefferie Abd , Wilkinson Arthur N.
Published: September 2021

The aim of this work was to improve the processability of triglycidyl-p-aminophenol (TGPAP) epoxy resin. To achieve this improvement, a diluent, the diglycidyl ether of bisphenol F (DGEBF or BPF), was added to TGPAP, and the blended epoxy was then cured with 4, 4′-diaminodiphenyl sulfones (DDS). A response surface methodology (RSM) was used, with the target response being to achieve a blended resin with a high glass transition temperature (Tg) and maximum pot life (or processing window, PW). Characterization through dynamic mechanical thermal analysis (DMTA) and using a rheometer indicated that the optimum formulation was obtained at 55.6 wt.% of BPF and a stoichiometric ratio of 0.60. Both values were predicted to give Tg at 180 °C and a processing window of up to 136.1 min. The predicted values were verified, with the obtained Tg and processing window (PW) being 181.2 ± 0.8 °C and 140 min, respectively, which is close to the values predicted using the RSM.
Development of a Rheology Die and Flow Characterization of Gas-Containing Polymer Melts
Authors: Kastner Clemens , Altmann Dominik , Kobler Eva , Steinbichler Georg
Published: September 2021

We present a novel measurement die for characterizing the flow behavior of gas-containing polymer melts. The die is mounted directly on the injection-molding cylinder in place of the mold cavity and thus enables near-process measurement of viscosity (i.e., under the conditions that would be present were a mold attached). This integration also resolves the issue of keeping gas-containing polymer melts under pressure during measurement to prevent desorption. After thermal characterization of the die, various correction approaches were compared against each other to identify the most suitable one for our case. We conducted measurements using polypropylene in combination with two different chemical blowing agents. Increasing the blowing-agent content to up to 6% revealed an interestingly low influence of gases on melt viscosity, which was confirmed by elongational viscosity measurements. For verification, we compared our results to corresponding measurements taken on a high-pressure capillary rheometer and found that they were in excellent agreement. Our die cannot only be used for rheological characterization. Combined with ultrasound sensors, it provides an innovative way of measuring the volumetric flow rate. This development represents an important step in improving the sustainability of gas-containing polymer processing.
Calibration of DEM for Cohesive Particles in the SLS Powder Spreading Process
Authors: Lupo Marco , Barletta Diego , Sofia Daniele , Poletto Massimo
Published: September 2021

In this paper, a new DEM calibration procedure based on two different types of procedures to compare simulation with experiments is proposed. The aim is to find the values of the interfacial adhesive surface energy and the coefficient of rolling friction between the particles to be used in the simulation. The approach adopted is the so-called Bulk Calibration method. The experimental values of the angle of repose and unconfined yield strength, found with a static testing method and by shear testing, respectively, are compared, respectively, with the angle of repose, found in a simulation reproducing the experimental procedure, and the unconfined yield strength, obtained from an idealized uniaxial testing procedure. The simulated DEM particles are spheres equipped with the Hertz Mindlin with JKR contact model. The results suggest that a bulk calibration approach is not able to provide results that are consistent with two simple bulk property evaluations and, therefore, direct ways to estimate the surface energy based on the evaluation of interparticle forces, for example, should preferably be adopted.
Dynamic Sales Price Control Model for Exclusive Exquisite Products within a Time Interval
Authors: Chen Po-Yu
Published: September 2021

When information regarding the effective evaluation of the value of exquisite products is lacking, the market demand function for such products at a given time point is affected by the diffusion of historical transaction price information before the time point. This is because historical transaction prices play an active role in influencing the internal reference price (IRP) of customers, and the continuous diffusion of historical transaction price information leads to the continuous correction, adjustment, and updating of customers’ IRPs. Given the varying rates of such information diffusion, the speed at which customers adjust their IRPs also varies across individuals and contexts. By considering the exponential distribution of potential customers’ IRPs as an example to establish the dynamic demand function that considers the effect of historical transaction prices, this paper discusses the effect of different information diffusion rates on the demand function at a time point. On the basis of this demand function, a sales price control model that maximizes the discounted profitability for businesses in the patent term of an exquisite product is then constructed to provide businesses with an operation method to cultivate prices and increase profits.
Effects of Pulse Voltage Duration on Open–Close Dynamic Characteristics of Solenoid Screw-In Cartridge Valves
Authors: Yue Daling , Li Linfei , Wei Liejiang , Liu Zengguang , Liu Chao , Zuo Xiukun
Published: September 2021

The hydraulic high-speed on/off valve (HSV)—the critical core component of digital hydraulic technology—has a special structural design and manufacture due to its fast opening and closing, which results in high prices and maintenance costs. The solenoid screw-in cartridge valve (SCV) is widely used in the hydraulic industry because of its merits, such as mature technology, reliable quality, and low cost. The contribution of this study is to replace the high-speed on/off valve with the SCV in some areas of application by introducing positive and negative pulse voltage control for the coil of the SCV, which only modifies the control circuit and needs no change in structure. Based on the analysis of the structure of the SCV, the simulation model was developed in AMESim and validated by experiments to investigate the effects of the pulse voltage duration on the open–close dynamic characteristics and find the optimal pulse voltage duration, so that the SCV can open or close in the shortest time to reduce energy loss as far as possible. The simulation results showed that the positive and negative pulse voltage could quicken the rising or declining speed of the coil current and dramatically decrease the opening and closing delay time. By the experimental comparison with the original control method, the opening time of the SCV decreased from 30 ms to 13 ms, and the closing time was reduced from 139 ms to 14 ms.
Understanding Folk Religiosity in the Philippines
Authors: Macaranas Juan Rafael G.
Published: September 2021

This paper argues for the appreciation of Filipino folk religiosity as part of cultivating authentic faith expressions among Filipinos. It presents historical, anthropological, sociocultural, and theological views on significant folk religious groups, traditions, and practices in the Philippines, including but not limited to the millenarian movements and popular Catholic feasts. Despite the varied influences and variegated Philippine culture, folk religiosity among Filipinos can be generalized as a syncretic blending of pre-colonial beliefs with the Catholic faith. As an academic and practicing Catholic, the researcher explores the folk religious elements present in the development of the millenarian movements, the unique faith expressions and influences behind folk Catholic feasts and celebrations, and probes deeper into the meaning of ordinary faith expressions. Coming from his own experiences and insights, he refers to previous scholarly works in discussing how spirituality or reverence to the sacred is inherently embedded in the folk religious ways, how the cultural Filipino traits manifest in the religious practices and vice versa, and how folk spirituality enables the expression of deep cultural and personal Christian faith experience. In conclusion, he maintains that millenarian movements are valid faith expressions that also celebrate independence and Filipino identity; traditional festivals and religious rites are the locals’ unique way of authentically expressing their faith, and; preserving folk religions and folk religiosity among Catholics is beneficial for engendering the growth of the faithful and the development of religion. A clear sense of folk religiosity is elemental in reappropriating religious dogmas and doctrines as the church and the faithful continuously study, dialogue, and fully experience life in the pursuit of approaching authenticity in faith, beliefs, and religions.
Muslim Stand-Up Comedy in the US and the UK: Incongruity, Everydayness, and Performativity
Authors: Aidi Lamiae
Published: September 2021

The objectives of this article are two-fold: to provide a review of the major figures and trends in Muslim American comedy and discuss certain techniques and approaches that have been used by stand-up comedians to counter predominant and discriminatory perceptions of the “Other”. To reiterate film critic Jack Shaheen’s argument in Reel Bad Arabs: How Hollywood Vilifies a People, the Western public is fed constructions of Islam as a “problem”; the terms “Arab” and “Muslim” are interchangeably used; Muslim men are depicted as “terrorists”; and Muslim women are depicted as “veiled and oppressed”. Much has been written on the generation and effect of stereotypes promoted by popular culture. However, stereotyped groups also use popular culture to speak for themselves. Popular culture also functions to resist, counter, push back against, and subvert stereotypes. In other words, the “Other” can speak for him or herself through popular culture as a means of contesting stereotypes that define Muslims and Arabs in terms of cultural and religious understandings that narrowly categorize individuals through attributes such as religiosity and femininity. This potential is being realized by second-generation Muslims familiar with the platforms created and provided by other marginalized groups in Anglo-American popular culture, and their work has come into its own especially in the aftermath of 9/11, a time that saw both the intensification of stereotypes and heightening of Muslim American consciousness. I concentrate on these specific stand-up comedians in the US and the UK, despite the fact that there are others in the diaspora who discuss Islamophobia, because these American and British comedians address all of the three most common stereotypes of Muslims: “Arab = Muslim”, the “terrorist”, and the “veiled and oppressed woman”.
An Action Research Framework for Religion and the Stigma of Suicide
Authors: Lehmann Curtis , Leung Carol , Miller Ivana , Girguis Samuel
Published: September 2021

Religious beliefs and practices have historically been intertwined with stigmatizing attitudes and responses to suicide, including stereotypes, prejudice, and discrimination. Understanding the relationship between religion and suicide stigma requires identifying specific religious beliefs and practices about suicide and how these are informed by broader worldviews, such as ethics, anthropology, and afterlife beliefs. Yet, research in this area has been complicated by the complex multidimensional nature of stigma and the diversity of religious beliefs and practices, even within religious traditions. Moreover, contrary arguments about the role of religious views of suicide in suicide prevention, specifically whether religious stigma is protective or instead contributes to risk, have obscured the interpretation of findings. This paper aims to advance research on this topic by first summarizing pertinent empirical findings and theoretical perspectives on public and personal stigma towards people with suicidal ideation (PWSI), people with suicidal behavior (PWSB), and suicide loss survivors (SLS). Secondly, a culturally nuanced action research framework (ARF) of religious stigma towards suicide is provided to guide future research. According to this ARF, research should advance strategically by investigating associations of religious beliefs and practices with stigmatization, identifying empowering resources within particular religious traditions, supporting suicide prevention efforts, and developing effective interventions to support PWSI, PWSB, and SLS. Moreover, such research efforts ought to equip religious leaders, and healthcare professionals working with religious individuals, to reduce stigma towards suicide and further the goal of suicide prevention.
“God Smiles”: The Rhythm of Revelation in Sorrentino’s “The Young Pope”
Authors: LaCouter Travis
Published: September 2021

The classic problematic of divine absence and presence is a familiar theological trope (deus absconditus). It achieves new life, however, in the work of contemporary Italian filmmaker Paolo Sorrentino (b. 1970), who explores the theme in his recent television miniseries The Young Pope (2016). I “read” Sorrentino as part of a trajectory in contemporary Italian theory (Vattimo, Agamben, etc.) that deconstructs-as-a-way-of-receiving certain traditional (especially Catholic) problematics. However, Sorrentino is to be distinguished from these others by what we might call a postmodern sincerity, whereby he manages to twist without breaking an orthodox understanding of divine invisibility. Importantly, Sorrentino emphasizes the interpersonal and ongoing nature of revelation, and thus situates the absconditus problem in a broader account of dialogical divine love. “Reading” Sorrentino in this way suggests that deus absconditus and deus revelatus are not concepts in tension but rather dynamic parts of an integral, integrating dialectic. It also suggests that visual storytelling remains a powerful medium for raising and indeed enacting fundamental theological questions to do with belief and unbelief.
Utilizing Authenticity: Options for Catholic Education in a Particular Detraditionalized Cultural Context
Authors: Rymarz Richard
Published: September 2021

This paper addresses some conceptual options for Catholic education in a particular cultural context. This context is where the Catholic school system is large, stable, and well established but in the wider cultural context, the place of religion in society is detraditionalized. This detraditionalization is reflected in Catholic school enrolments where increasing numbers of students come from non-Catholic backgrounds, where, amongst Catholics, engagement with traditional structures is low or where there is no religious association at all. To initiate discussion a simple dichotomy is introduced; do Catholic schools promote religious identity or do they address a wider demographic by stressing harmonized common values and policies? To elaborate on this initial position several conceptual perspectives are offered. A key discussion point centres around the human community of Catholic schools and how they align with the various options that are proposed.
Persona in spe. Anthropological and Theodical Aspects of Hope
Authors: Gudaniec Arkadiusz
Published: September 2021

I intend to reflect on three phenomena that are revealed in the personal experience of hope: (1) hope distinguishes a person from the natural context, but it does so through nature, i.e., based on desires rooted in human nature; (2) hope is not only inscribed in the existential situation of human being, but also expresses the very meaning of human transcendence: the person transcends themself, because they live the hope of fulfillment in the transcendent reality; hope is a foretaste of a higher, more perfect life; (3) hope is a person’s deeply experienced expectation of love, that is, of someone who loves. The above phenomena require a justification, which is the answer to the question “what is the reason for experiencing hope?”. Carrying out analyses on the basis of the modernized metaphysics of the person, I refer primarily to the concept of personal acts, to the concept of religiosity as an essential property of the person and to elements of the concept of love. The conclusions of these analyses indicate the necessity of accepting the real existence of the object of human hope, since personal life essentially goes beyond contingency, towards wholeness in the form of union with Someone who loves.
Experts in Self-Isolation? Monastic Outreach during Lockdown
Authors: Irvine Richard D.G.
Published: September 2021

This paper draws on digital ethnography to examine the experience of a Catholic English Benedictine monastery in the context of restrictions on religious gatherings during the global COVID-19 pandemic. As the monks expand their digital presence and social media involvement, it is their experience of social withdrawal and apparent expertise in self-isolation that provides the grounding for their public engagement. While Max Weber depicts the monk as a world-transcending “virtuoso”, in a time of lockdown, this separation from the world provides a point of connection with the experience of wider society.
A Geminated Mandibular Second Molar—A Case Report
Authors: Pandya-Sharpe Asha , Puryer James
Published: September 2021

Fusion and gemination are not entirely uncommon dental anomalies that may also be named ‘double teeth’. This is due to their unusual presentation in a twin-like fashion. Teeth with these irregularities may appear clinically similar, presenting as large and bulbous in shape with unusual anatomy and fissure patterns. The exact aetiology of these anomalies is uncertain, but many potential local or systemic disturbances during the morphodifferentiation stage of odontogenesis have been considered. Gemination occurs rarely in the permanent dentition and even less frequently in the posterior region of the oral cavity. This report presents a case of a geminated mandibular second molar and discusses the importance of early recognition and diagnosis of such teeth so that adequate preventative care and treatment can be provided.
ESG Disclosure and Portfolio Performance
Authors: Bermejo Climent Ramón , Garrigues Isabel Figuerola-Ferretti , Paraskevopoulos Ioannis , Santos Alvaro
Published: September 2021

This paper illustrates the impact of Environmental Social and Governance (ESG) disclosure on European corporate equity performance. In this study, we use an extensive data set of European ESG ratings provided by Bloomberg to demonstrate that ESG disclosure is associated with improved return growth, with the Governance pillar exhibiting the strongest effect on corporate performance. The impact of ESG disclosure on volatility is changing over time, suggesting that the existence of opaque ratings limits the transmission of information disclosure into corporate performance.
Automatic Detection of Inland Water Bodies along Altimetry Tracks for Estimating Surface Water Storage Variations in the Congo Basin
Authors: Frappart Frédéric , Zeiger Pierre , Betbeder Julie , Gond Valéry , Bellot Régis , Baghdadi Nicolas , Blarel Fabien , Darrozes José , Bourrel Luc , Seyler Frédérique
Published: September 2021

Surface water storage in floodplains and wetlands is poorly known from regional to global scales, in spite of its importance in the hydrological and the carbon balances, as the wet areas are an important water compartment which delays water transfer, modifies the sediment transport through sedimentation and erosion processes, and are a source for greenhouse gases. Remote sensing is a powerful tool for monitoring temporal variations in both the extent, level, and volume, of water using the synergy between satellite images and radar altimetry. Estimating water levels over flooded area using radar altimetry observation is difficult. In this study, an unsupervised classification approach is applied on the radar altimetry backscattering coefficients to discriminate between flooded and non-flooded areas in the Cuvette Centrale of Congo. Good detection of water (open water, permanent and seasonal inundation) is above 0.9 using radar altimetry backscattering from ENVISAT and Jason-2. Based on these results, the time series of water levels were automatically produced. They exhibit temporal variations in good agreement with the hydrological regime of the Cuvette Centrale. Comparisons against a manually generated time series of water levels from the same missions at the same locations show a very good agreement between the two processes (i.e., RMSE ≤ 0.25 m in more than 80%/90% of the cases and R ≥ 0.95 in more than 95%/75% of the cases for ENVISAT and Jason-2, respectively). The use of the time series of water levels over rivers and wetlands improves the spatial pattern of the annual amplitude of water storage in the Cuvette Centrale. It also leads to a decrease by a factor of four for the surface water estimates in this area, compared with a case where only time series over rivers are considered.
The Response and Feedback of Ocean Mesoscale Eddies to Four Sequential Typhoons in 2014 Based on Multiple Satellite Observations and Argo Floats
Authors: Li Jiagen , Zhang Han , Liu Shanshan , Wang Xiuting , Sun Liang
Published: September 2021

Four sequential tropical cyclones generated and developed in the Northwest Pacific Ocean (NWP) in 2014, which had significant impacts on the oceanic environment and coastal regions. Based on a substantial dataset of multiple-satellite observations, Argo profiles, and reanalysis data, we comprehensively investigated the interactions between the oceanic environment and sequential tropical cyclones. Super typhoon Neoguri (2014) was the first typhoon-passing studied area, with the maximum sustained wind speed of 140 kts, causing strong cold wake along the track. The location of the strongest cold wake was consistent with the pre-existing cyclonic eddy (CE), in which the average sea surface temperature (SST) cooling exceeded −5 °C. Subsequently, three tropical cyclones passed the ocean environment left by Neoguri, namely, the category 2 typhoon Matmo (2014), the tropical cyclone Nakri (2014) and the category 5 typhoon Halong (2014), which caused completely different subsequent responses. In the CE, due to the fact that the ocean stratification was strongly destroyed by Neoguri and difficult to recover, even the weak Nakri could cause a secondary response, but the secondary SST cooling would be overridden by the first response and thus could cause no more serious ocean disasters. If the subsequent typhoon was super typhoon Halong, it could cause an extreme secondary SST cooling, exceeding −8 °C, due to the deep upwelling, exceeding 700 m, surpassing the record of the maximum cooling caused by the first typhoon. In the anti-cyclonic eddy (AE), since the first typhoon Neoguri caused strong seawater mixing, it was difficult for the subsequent weak typhoons to mix the deeper, colder and saltier water into the surface, thus inhibiting secondary SST cooling, and even the super typhoon Halong would only cause as much SST cooling as the first typhoon. Therefore, the ocean responses to sequential typhoons depended on not only TCs intensity, but also TCs track order and ocean mesoscale eddies. In turn, the cold wake caused by the first typhoon, Neoguri, induced different feedback effects on different subsequent typhoons.
The Potential of Multispectral Imagery and 3D Point Clouds from Unoccupied Aerial Systems (UAS) for Monitoring Forest Structure and the Impacts of Wildfire in Mediterranean-Climate Forests
Authors: Reilly Sean , Clark Matthew L. , Bentley Lisa Patrick , Matley Corbin , Piazza Elise , Oliveras Menor Imma
Published: September 2021

Wildfire shapes vegetation assemblages in Mediterranean ecosystems, such as those in the state of California, United States. Successful restorative management of forests in-line with ecologically beneficial fire regimes relies on a thorough understanding of wildfire impacts on forest structure and fuel loads. As these data are often difficult to comprehensively measure on the ground, remote sensing approaches can be used to estimate forest structure and fuel load parameters over large spatial extents. Here, we analyze the capabilities of one such methodology, unoccupied aerial system structure from motion (UAS-SfM) from digital aerial photogrammetry, for mapping forest structure and wildfire impacts in the Mediterranean forests of northern California. To determine the ability of UAS-SfM to map the structure of mixed oak and conifer woodlands and to detect persistent changes caused by fire, we compared UAS-SfM derived metrics of terrain height and canopy structure to pre-fire airborne laser scanning (ALS) measurements. We found that UAS-SfM was able to accurately capture the forest’s upper-canopy structure, but was unable to resolve mid- and below-canopy structure. The addition of a normalized difference vegetation index (NDVI) ground point filter to the DTM generation process improved DTM root-mean-square error (RMSE) by ~1 m with an overall DTM RMSE of 2.12 m. Upper-canopy metrics (max height, 95th percentile height, and 75th percentile height) were highly correlated between ALS and UAS-SfM (r > +0.9), while lower-canopy metrics and metrics of density and vertical variation had little to no similarity. Two years after the 2017 Sonoma County Tubbs fire, we found significant decreases in UAS-SfM metrics of bulk canopy height and NDVI with increasing burn severity, indicating the lasting impact of the fire on vegetation health and structure. These results point to the utility of UAS-SfM as a monitoring tool in Mediterranean forests, especially for post-fire canopy changes and subsequent recovery.
Accuracy Assessment of UAV-Photogrammetric-Derived Products Using PPK and GCPs in Challenging Terrains: In Search of Optimized Rockfall Mapping
Authors: Žabota Barbara , Kobal Milan
Published: September 2021

Unmanned aerial photogrammetric surveys are increasingly being used for mapping and studying natural hazards, such as rockfalls. Surveys using unmanned aerial vehicles (UAVs) can be performed in remote, hardly accessible, and dangerous areas, while the photogrammetric-derived products, with high spatial and temporal accuracy, can provide us with detailed information about phenomena under consideration. However, as photogrammetry commonly uses indirect georeferencing through bundle block adjustment (BBA) with ground control points (GCPs), data acquisition in the field is not only time-consuming and labor-intensive, but also extremely dangerous. Therefore, the main goal of this study was to investigate how accurate photogrammetric products can be produced by using BBA without GCPs and auxiliary data, namely using the coordinates X0, Y0 and Z0 of the camera perspective centers computed with PPK (Post-Processing Kinematic). To this end, orthomosaics and digital surface models (DSMs) were produced for three rockfall sites by using images acquired with a DJI Phantom 4 RTK and the two different BBA methods mentioned above (hereafter referred to as BBA_traditional and BBA_PPK). The accuracy of the products, in terms of the Root Mean Square Error (RMSE), was computed by using verification points (VPs). The accuracy of both BBA methods was also assessed. To test the differences between the georeferencing methods, two statistical test were used, namely a paired Student’s t-test, and a non-parametric Wilcoxon signed-rank. The results show that the accuracy of the BBA_PPK is inferior to that of BBA_traditional, with the total RMSE values for the three sites being 0.056, 0.066, and 0.305 m, respectively, compared to 0.019, 0.036 and 0.014 m obtained with BBA_traditional. The accuracies of the BBA methods are reflected in the accuracy of the orthomosaics, whose values for the BBA_PPK are 0.039, 0.043 and 0.157 m, respectively, against 0.029, 0.036 and 0.020 m obtained with the BBA_traditional. Concerning the DSM, those produced with the BBA_PPK method present accuracy values of 0.065, 0.072 and 0.261 m, respectively, against 0.038, 0.060 and 0.030 m obtained with the BBA_traditional. Even though that there are statistically significant differences between the georeferencing methods, one can state that the BBA_PPK presents a viable solution to map dangerous and exposed areas, such as rockfall transit and deposit areas, especially for applications at a regional level.
A Coarse-to-Fine Contour Optimization Network for Extracting Building Instances from High-Resolution Remote Sensing Imagery
Authors: Fang Fang , Wu Kaishun , Liu Yuanyuan , Li Shengwen , Wan Bo , Chen Yanling , Zheng Daoyuan
Published: September 2021

Building instances extraction is an essential task for surveying and mapping. Challenges still exist in extracting building instances from high-resolution remote sensing imagery mainly because of complex structures, variety of scales, and interconnected buildings. This study proposes a coarse-to-fine contour optimization network to improve the performance of building instance extraction. Specifically, the network contains two special sub-networks: attention-based feature pyramid sub-network (AFPN) and coarse-to-fine contour sub-network. The former sub-network introduces channel attention into each layer of the original feature pyramid network (FPN) to improve the identification of small buildings, and the latter is designed to accurately extract building contours via two cascaded contour optimization learning. Furthermore, the whole network is jointly optimized by multiple losses, that is, a contour loss, a classification loss, a box regression loss and a general mask loss. Experimental results on three challenging building extraction datasets demonstrated that the proposed method outperformed the state-of-the-art methods’ accuracy and quality of building contours.
Soil Salinization Level Monitoring and Classifying by Mixed Chaotic Systems
Authors: Tian Anhong , Fu Chengbiao , Yau Her-Terng , Su Xiao-Yi , Xiong Heigang
Published: September 2021

Soil salinization process is a complex non-linear dynamic evolution. To classify a system with this type of non-linear characteristic, this study proposed a mixed master/slave chaotic system based on Chua’s circuit and a fractional-order Chen-Lee chaotic system to classify soil salinization level. The subject is the soil in Xinjiang with different levels of human interference. A fractional-order Chen-Lee chaotic system was constructed, and the spectral signal processed by the Chua’s non-linear circuit was substituted into the master/slave chaotic system. The chaotic dynamic errors with different fractional orders were calculated. The comparative analysis showed that 0.1-order has the largest chaotic dynamic error change, which produced two distinct and divergent results. Thus, this study converted the chaotic dynamic errors of fractional 0.1-order into chaotic attractors to build an extension matter-element model. Finally, we compared the soil salt contents (SSC) from the laboratory chemical analysis with the results of the extension theory classification. The comparison showed that the combination of fractional order mixed master/slave chaotic system and extension theory has high classification accuracy for soil salinization level. The results of this system match the result of the chemical analysis. The classification accuracy of the calibration set data was 100%, and the classification accuracy of the validation set data was 90%. This method is the first use of the mixed master/slave chaotic system in this field and can satisfy certain soil salinization monitoring needs as well as promote the application of the chaotic system in soil salinization monitoring.
Hydrometeor and Latent Heat Nudging for Radar Reflectivity Assimilation: Response to the Model States and Uncertainties
Authors: Huo Zhaoyang , Liu Yubao , Wei Ming , Shi Yueqin , Fang Chungang , Shu Zhuozhi , Li Yang
Published: September 2021

Radar data are essential to convection nowcasting and nudging-based radar data assimilation through diabatic initialization is one of the most effective approaches for forecasting convective systems with numerical weather prediction (NWP) models, used at several advanced global weather centers. It is desired to assess the uncertainty and physical consistency of this assimilation process. This paper investigated impacts of relaxation coefficient, radar data update intervals and continuous assimilation time duration and addressed the key issues and possible solutions of the radar data assimilation based on the WRF hydrometeor and latent heat nudging (HLHN) developed at the National Center for Atmospheric Research (NCAR). It is revealed that excessively large relaxation coefficient forced the model to observations with a tendency greater than the physical terms of the convection, causing the dynamic imbalances and serious convection “ramp-down” right after the free forecast starts. Assimilating high update frequency radar data can make the tendency terms moderate and sustained thereby maintaining the assimilation effect and reducing fortuitous convection. HLHN requires a minimum continuous assimilation duration to contain the initial forced disturbance of the model. For a summer Meiyu precipitation case studied, the minimum duration is ~1 h. Appropriate selection of the HLHN parameters is able to effectively improve the temperature, humidity, and dynamic fields of the model. In addition, several issues still remain to be solved to further enhance HLHN.
Early-Season Mapping of Winter Crops Using Sentinel-2 Optical Imagery
Authors: Tian Haifeng , Wang Yongjiu , Chen Ting , Zhang Lijun , Qin Yaochen
Published: September 2021

Sentinel-2 imagery is an unprecedented data source with high spatial, spectral and temporal resolution in addition to free access. The objective of this paper was to evaluate the potential of using Sentinel-2 data to map winter crops in the early growth stage. Analysis of three winter crop types—winter garlic, winter canola and winter wheat—was carried out in two agricultural regions of China. We analysed the spectral characteristics and vegetation index profiles of these crops in the early growth stage and other land cover types based on Sentinel-2 images. A decision tree classification model was built to distinguish the crops based on these data. The results demonstrate that winter garlic and winter wheat can be distinguished four months before harvest, while winter canola can be distinguished two months before harvest. The overall classification accuracy was 96.62% with a kappa coefficient of 0.95. Therefore, Sentinel-2 images can be used to accurately identify these winter crops in the early growth stage, making them an important data source in the field of agricultural remote sensing.
Spatial and Temporal Variation Characteristics of Heatwaves in Recent Decades over China
Authors: Liu Jinping , Ren Yanqun , Tao Hui , Shalamzari Masoud Jafari
Published: September 2021

Global warming and rapid socioeconomic development increased the risk of regional and global disasters. Particularly in China, annual heatwaves (HWs) caused many fatalities and substantial property damage, with an increasing trend. Therefore, it is of great scientific value and practical importance to analyze the spatiotemporal changes of HW in China for the sustainable development of regional socioeconomic and disaster risk management. In this study, based on gridded maximum temperature product and specific humidity dataset, an HW evaluation algorithm, considering the impact of humidity on the human body and the characteristics of HW in China, was employed to generate daily HW state at light, moderate, and severe levels for the period 1979–2018. Consequently, the regional differences at three HW levels were revealed, and the changing trend of HW onset, termination, and duration in each subregion was analyzed. The results show that in the three levels, the frequency and duration of HW in China had a significant increasing trend, generally characterized by the advancement of HW onset and the postponement of HW termination. The HW influence at light, moderate and severe levels decreased gradually, with the light level occurring the earliest and terminating the latest. Among the seven subregions, the largest HW frequency happened to be mainly in XJ (Xinjiang), SC (Southern China), and NC (Northern China), while the variations of HW onset and termination had noticeable regional differences at the three levels. The findings presented in this study can provide the essential scientific and technological support for national and regional disaster prevention mitigation and adaptation to extreme climate events.
ME-Net: A Multi-Scale Erosion Network for Crisp Building Edge Detection from Very High Resolution Remote Sensing Imagery
Authors: Wen Xiang , Li Xing , Zhang Ce , Han Wenquan , Li Erzhu , Liu Wei , Zhang Lianpeng
Published: September 2021

The detection of building edges from very high resolution (VHR) remote sensing imagery is essential to various geo-related applications, including surveying and mapping, urban management, etc. Recently, the rapid development of deep convolutional neural networks (DCNNs) has achieved remarkable progress in edge detection; however, there has always been the problem of edge thickness due to the large receptive field of DCNNs. In this paper, we proposed a multi-scale erosion network (ME-Net) for building edge detection to crisp the building edge through two innovative approaches: (1) embedding an erosion module (EM) in the network to crisp the edge and (2) adding the Dice coefficient and local cross entropy of edge neighbors into the loss function to increase its sensitivity to the receptive field. In addition, a new metric, Ene, to measure the crispness of the predicted building edge was proposed. The experiment results show that ME-Net not only detects the clearest and crispest building edges, but also achieves the best OA of 98.75%, 95.00% and 95.51% on three building edge datasets, and exceeds other edge detection networks 3.17% and 0.44% at least in strict F1-score and Ene. In a word, the proposed ME-Net is an effective and practical approach for detecting crisp building edges from VHR remote sensing imagery.
Hyperspectral Image Denoising via Framelet Transformation Based Three-Modal Tensor Nuclear Norm
Authors: Kong Wenfeng , Song Yangyang , Liu Jing
Published: September 2021

During the acquisition process, hyperspectral images (HSIs) are inevitably contaminated by mixed noise, which seriously affects the image quality. To improve the image quality, HSI denoising is a critical preprocessing step. In HSI denoising tasks, the method based on low-rank prior has achieved satisfying results. Among numerous denoising methods, the tensor nuclear norm (TNN), based on the tensor singular value decomposition (t-SVD), is employed to describe the low-rank prior approximately. Its calculation can be sped up by the fast Fourier transform (FFT). However, TNN is computed by the Fourier transform, which lacks the function of locating frequency. Besides, it only describes the low-rankness of the spectral correlations and ignores the spatial dimensions’ information. In this paper, to overcome the above deficiencies, we use the basis redundancy of the framelet and the low-rank characteristics of HSI in three modes. We propose the framelet-based tensor fibered rank as a new representation of the tensor rank, and the framelet-based three-modal tensor nuclear norm (F-3MTNN) as its convex relaxation. Meanwhile, the F-3MTNN is the new regularization of the denoising model. It can explore the low-rank characteristics of HSI along three modes that are more flexible and comprehensive. Moreover, we design an efficient algorithm via the alternating direction method of multipliers (ADMM). Finally, the numerical results of several experiments have shown the superior denoising performance of the proposed F-3MTNN model.
Hyperspectral and Full-Waveform LiDAR Improve Mapping of Tropical Dry Forest’s Successional Stages
Authors: Zhao Genping , Sanchez-Azofeifa Arturo , Laakso Kati , Sun Chuanliang , Fei Lunke
Published: September 2021

Accurate estimation of the degree of regeneration in tropical dry forest (TDF) is critical for conservation policymaking and evaluation. Hyperspectral remote sensing and light detection and ranging (LiDAR) have been used to characterize the deterministic successional stages in a TDF. These successional stages, classified as early, intermediate, and late, are considered a proxy for mapping the age since the abandonment of a given forest area. Expanding on the need for more accurate successional forest mapping, our study considers the age attributes of a TDF study area as a continuous expression of relative attribute scores/levels that vary along the process of ecological succession. Specifically, two remote-sensing data sets: HyMap (hyperspectral) and LVIS (waveform LiDAR), were acquired at the Santa Rosa National Park Environmental Monitoring Super Site (SRNP-EMSS) in Costa Rica, were used to generate age-attribute metrics. These metrics were then used as entry-level variables on a randomized nonlinear archetypal analysis (RNAA) model to select the most informative metrics from both data sets. Next, a relative attribute learning (RAL) algorithm was adapted for both independent and fused metrics to comparatively learn the relative attribute levels of the forest ages of the study area. In this study, four HyMap indices and five LVIS metrics were found to have the potential to map the forest ages of the study area, and compared with these results, a significant improvement was found through the fusion of the metrics on the accuracy of the generated forest age maps. By linking the age group mapping and the relative attribute mapping results, a dynamic gradient of the age-attribute transition patterns emerged.
A Study on Brightness Reversal of Internal Waves in the Celebes Sea Using Himawari-8 Images
Authors: Hu Beilei , Meng Junmin , Sun Lina , Zhang Hao
Published: September 2021

A geostationary meteorological satellite is located at a fixed point above the equator, which can continuously observe internal waves and provides great advantages in research on changes in the generation and propagation of internal waves. The scale of internal waves in the Celebes Sea is large, which is still very obvious in geostationary meteorological satellite images with a lower spatial resolution. This study considers continuous remote sensing images of geostationary meteorological satellite Himawari-8 to analyze the bright and dark features of internal waves in the Celebes Sea in optical remote sensing images. The solar zenith angle, sensor zenith angle and relative azimuth angle of internal waves in six images are calculated, and the changes are 12.45°, 0.20° and 3.44°, respectively, within 50 min. Moreover, based on the normalized sunglint radiance theory, the critical solar viewing angle is proposed and verified. The results indicate that the bright and dark features of internal waves when passing through sunglint and non-sunglint areas are greatly reversed, and the critical solar viewing angles are 18.73° and 27.41°, respectively. In this study, geostationary meteorological satellite Himawari-8 images are analyzed to study on the brightness reversal phenomenon of internal waves for the first time, and a unique brightness change in internal waves during the propagation process is revealed, which has not been reported in existing research.