bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and Characterization of Porous Carbon Composites from Oil-Containing Sludge by a Pyrolysis-Activation Process
Authors: Tsai Wen-Tien , Lin Yu-Quan
Published: April 2022

Large amounts of oil-containing sludge (OS) are produced in the energy, industry and services sectors. It is mainly composed of residual oil and particulate matter, thus posing an environmental threat and leading to resource depletion if it is improperly handled. In this work, the OS feedstock was thermally treated to produce porously magnetic carbon composites (CC) using a pyrolysis-activation process. Using the data on the thermogravimetric analysis (TGA) of the OS feedstock, the thermal activation experiments were performed at 850 °C as a function of residence time (30, 60 and 90 min). The results of pore analysis for the resulting CC products showed that the Brunauer–Emmett–Teller (BET) surface area greatly decreased from 21.59 to 0.56 m2/g with increasing residence time from 30 to 90 min. This decline could be associated with continuous gasification by CO2, thus causing the removal of limited carbon on the surface of CC for a longer reaction time. Furthermore, the physical properties of the resulting CC products can be enhanced by post acid-washing due to the development of new pores from the leaching-out of inorganic minerals. The BET surface area increased from 21.59 to 40.53 m2/g at the residence time of 30 min. Obviously, the resulting CC products were porous materials with mesopores and macropores that were concurrently formed from the thermal activation treatment. These porous features were also observed by scanning electron microscopy (SEM).
A Lean Manufacturing Progress Model and Implementation for SMEs in the Metal Products Industry
Authors: Huang Chien-Yi , Lee Dasheng , Chen Shu-Chuan , Tang William
Published: April 2022

The manufacturing industry faces the challenge of small and diversified customer orders. To meet this challenge, strong internal production capabilities are required. A lean manufacturing process that uses fewer resources and offers greater process improvement will help SMEs to continue to contribute to the global economy. Though SMEs provide most employment opportunities, previous studies have focused on large companies in auto-manufacturing-related industries. With the commitment and support of the management, and the application of a value stream map (VSM) and related improvement tools, we produced a practical process improvement model for a lean manufacturing system in an SME. With the commitment and support of the management and the joint efforts of the project improvement staff, the 10 improvement projects over a six-month period all achieved their goals: reduction in lead time from 26 days to 19.5 days, improvement of welding per people per hour (PPH) efficiency by 28.3%, improvement of packaging PPH efficiency by 64.1%, improvement of working in process (WIP) efficiency at the production site by 83.84%, and improvement of raw material storage by 83.84%. The efficiency of the raw material warehouse inventory was improved by 58.63%, and the efficiency of the shipment completion rate was improved by 14.5%.
Multi-Omics Integrative Approach of Extracellular Vesicles: A Future Challenging Milestone
Authors: Shaba Enxhi , Vantaggiato Lorenza , Governini Laura , Haxhiu Alesandro , Sebastiani Guido , Fignani Daniela , Grieco Giuseppina Emanuela , Bergantini Laura , Bini Luca , Landi Claudia
Published: April 2022

In the era of multi-omic sciences, dogma on singular cause-effect in physio-pathological processes is overcome and system biology approaches have been providing new perspectives to see through. In this context, extracellular vesicles (EVs) are offering a new level of complexity, given their role in cellular communication and their activity as mediators of specific signals to target cells or tissues. Indeed, their heterogeneity in terms of content, function, origin and potentiality contribute to the cross-interaction of almost every molecular process occurring in a complex system. Such features make EVs proper biological systems being, therefore, optimal targets of omic sciences. Currently, most studies focus on dissecting EVs content in order to either characterize it or to explore its role in various pathogenic processes at transcriptomic, proteomic, metabolomic, lipidomic and genomic levels. Despite valuable results being provided by individual omic studies, the categorization of EVs biological data might represent a limit to be overcome. For this reason, a multi-omic integrative approach might contribute to explore EVs function, their tissue-specific origin and their potentiality. This review summarizes the state-of-the-art of EVs omic studies, addressing recent research on the integration of EVs multi-level biological data and challenging developments in EVs origin.
US Nurses’ Challenges with Personal Protective Equipment during COVID-19: Interview Findings from the Frontline Workforce
Authors: Simonovich Shannon D. , Aquino Elizabeth , Lattner Christina , Soco Cheryl , Ponder Tiffany N. , Amer Lily , Howard Stephanie , Nwafor Gilliane , Shah Payal , Badowski Donna , Krawczyk Susan , Mueller Wiesemann Lucy , Spurlark Roxanne S. , Webber-Ritchey Kashica J. , Lee Young-Me
Published: April 2022

This study aimed to describe nurses’ experiences with personal protective equipment while providing patient care during the first wave of the COVID-19 pandemic in the US. From May 2020 to September 2020, 100 individual interviews were conducted with nurses from diverse backgrounds and practice settings. Interviews were audio-recorded, transcribed, and verified for thematic analysis. Three key themes emerged related to personal protective equipment during COVID-19: (1) concerns with safety, (2) concerns with personal protective equipment supply, and (3) concerns with health care systems changing personal protective equipment policies. These findings support the importance of transparent and equitable institution-wide PPE standards in creating safe working environments. Clear communication around personal protective equipment policies and procedures, personal protective equipment education, and assurance of equitable access to equipment that can mitigate risk and disability while also reducing fear, confusion, and frustration among nurses. Maintaining clear and consistent personal protective equipment guidelines and communication regarding supplies and procedures enhances transparency during both routine and critical times de-escalating the inevitable strain concomitant with providing patient care during a global pandemic.
Correction of the Scientific Production: Publisher Performance Evaluation Using a Dataset of 4844 PubMed Retractions
Authors: Toma Catalin , Padureanu Liliana , Toma Bogdan
Published: April 2022

Background. Retraction of problematic scientific articles after publication is one of the mechanisms for correcting the literature available to publishers. The market volume and the busi-ness model justify publishers’ ethical involvement in the post-publication quality control (PPQC) of human-health-related articles. The limited information about this subject led us to analyze Pub-Med-retracted articles and the main retraction reasons grouped by publisher. We propose a score to appraise publisher’s PPQC results. The dataset used for this article consists of 4844 Pub-Med-retracted papers published between 1.01.2009 and 31.12.2020. Methods. An SDTP score was constructed from the dataset. The calculation formula includes several parameters: speed (article exposure time (ET)), detection rate (percentage of articles whose retraction is initiated by the edi-tor/publisher/institution without the authors’ participation), transparency (percentage of retracted articles available online and the clarity of the retraction notes), and precision (mention of authors’ responsibility and percentage of retractions for reasons other than editorial errors). Results. The 4844 retracted articles were published in 1767 journals by 366 publishers, the average number of retracted articles/journal being 2.74. Forty-five publishers have more than 10 retracted articles, holding 88% of all papers and 79% of journals. Combining our data with data from another study shows that less than 7% of PubMed dataset journals retracted at least one article. Only 10.5% of the retraction notes included the individual responsibility of the authors. Nine of the top 11 publishers had the largest number of retracted articles in 2020. Retraction-reason analysis shows considerable differences between publishers concerning the articles’ ET: median values between 9 and 43 months (mistakes), 9 and 73 months (images), and 10 and 42 months (plagiarism and overlap). The SDTP score shows, from 2018 to 2020, an improvement in PPQC of four publishers in the top 11 and a decrease in the gap between 1st and 11th place. The group of the other 355 publishers also has a positive evolution of the SDTP score. Conclusions. Publishers have to get involved actively and measurably in the post-publication evaluation of scientific products. The introduction of reporting standards for retraction notes and replicable indicators for quantifying publishing QC can help increase the overall quality of scientific literature.
Discovery of X-rays—Its Impact in India and History of X-ray Research in Colonial India
Authors: Roy Suprakash C.
Published: April 2022

India holds a respectable position globally in X-ray research, particularly in X-ray crystallography. X-ray research in India is as old as the discovery of X-rays and the history of X-ray research in colonial India is fascinating. The purpose of this paper is to present how India participated in X-ray research and how X-ray research initiated by C.V. Raman, the only Indian Nobel Laureate in physics, at the Indian Association for the Cultivation of Science (IACS) paved the way to proliferate X-ray research in all parts of India and acted as the foundation stone of modern X-ray research in India. With limited resources under the British rule (India became independent in 1947), readers will find that the research work performed by Indians is commendable. This article is neither comprehensive nor detailed but will give the readers a flavour of the high-quality X-ray research that was performed in India in the early years after the discovery of X-rays.
The Physical Characterization and Terminal Velocities of Aluminium, Iron and Plastic Bottle Caps in a Water Environment
Authors: Nikolaev Alexander A.
Published: April 2022

Aluminium, iron and plastic are materials which are extensively used at both industry and individual levels. However, significant amounts of aluminium, iron and plastic end up in the environment. Specifically, bottle caps made of these materials are often thrown away, with or without bottles, and appear among the common plastic debris entering the world’s oceans and beaches. More than 20 million bottle caps and lids have been identified during beach-cleaning campaigns over the last 30 years. To recover bottle caps from the shores, conventional technologies can be used. In this paper, the physical properties of used metal and plastic bottle caps were examined and related to the settling and rising velocities of the caps, as well as their drag coefficients and hydrodynamic modes in water environments, with respect to gravity separation. The sample contained aluminium, iron, high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP) bottle caps. The findings revealed that the density differences between the bottle caps resulted in the terminal settling velocities of aluminium and iron particles, which were significantly higher than the rising velocities of the plastic caps. The results allowed us to design a flowsheet for bottle cap recovery from beach coasts in order to reduce environmental impact and produce add-on plastic and metal products.
Daigidan: The Great Ball of Doubt
Authors: Timmerman Peter
Published: April 2022

In some forms of Zen Buddhism, the aspiring student is given a problem to solve, whether it be a paradoxical koan, a probing question about the self, or some personal dilemma to which there appears to be no answer. This struggle of the student towards enlightenment is described as the creation in the student of a great mass or ball of doubt, called a daigidan. The more and more the student struggles with this problem, the more he or she becomes frustrated, lost, blocked, enmeshed and burdened down by this growing ball of doubt. Every examination of the problem reveals new difficulties; confusion ensnarls the world; the strings and strands of doubt multiply until the point is reached where everything in the universe seems to be entangled and paralyzed—all tied up in knots. Moreover, it is said that the greater the ball of doubt grows, the greater the moment of awakening when at last it finally comes. Into our hands, in our time, has been given a Great Ball of Doubt, perhaps the greatest ball of doubt there could possibly be: the Earth. It is an immense koan, the solution for which we are now, like Zen students, intensely and personally responsible: that is, our lives and futures depend on our being able to unravel the knots of its mysterious burden. The solving of such a mystery is internal to it (unlike a problem that stands outside of us), and the realization that the planet has finite boundaries has caused an “implosion of sensibility”—a vast cultural struggle between those who have internalized this finiteness, and those who still persist in believing in an infinite planet, with infinite resources, occupied by humans with infinite desires. Instead, in order to solve this immense all-engulfing koan, we are being driven into new (and sometimes very old) forms of planetary embeddedness and immanence, and away from flights to some kind of irresponsible imaginary ranscendence.
Religion, Animals, and Black Theology: The Spiritual Praxis of Sparing
Authors: Calloway Jamall A.
Published: April 2022

This article compares an interspecies moment in Howard Thurman’s classic text, Jesus and the Disinherited, and Gwendolyn Brook’s novella, Maud Martha, to consider how Black liberation theology might reimagine the animal-human binarism it has assumed from the Western Philosophical tradition. I contend that an animal-human binarism attenuates the liberationist ethos of black theology, particularly when the animal is centered. To explore this, I first parse out the theological anthropology of Black liberation theology to demonstrate how it has historically occupied a complicated relationship to Western depictions of the human. Then, I argue on the grounds of its own theological convictions, that black theology is obligated to move beyond this ambivalence. As an example, I assess Howard Thurman’s classic essay to discover what insights might be revealed if we reconsider his reading of the mouse’s squeal, considering a comparison to a similar encounter between a human and a pest in Gwendolyn Brook’s novella, Maud Martha. This comparison reveals that Thurman may very well be limited in his capacity to recognize something in the mouse’s defiance. On the other hand, Brooks’ ecowomanist lens may better affirm the defiant mouse. Maud Martha identifies with the mouse so much that she, in contrast to Thurman, spares its life. This moment resulted in her undergoing an unexpected spiritual experience. This experience, according to my reading, is an example of what I am describing as “catching a glimpse” of a liberating deity’s interiority or, what I am considering as a new relation with divine immanence. In other words, in sparing the animal, in seeing the animal as of equal significance, she consequently felt a connection with God. This moment of liberation and divine connection is the ultimate aim of Black liberation theology. An aim we can try to reach by including the animal into our liberationist objective.
Hybridising Minjian Religion in South China: Participants, Rituals, and Architecture
Authors: Guo Huanyu , Wang Canglong , Nie Youping , Tang Xiaoxiang
Published: April 2022

This study focuses on the ongoing hybridisation of minjian (folk or popular, literally “among the people”) religious activities in rural areas of south China. It demonstrates recent changes in religious hybridisation through extensive fieldwork in two villages. It also investigates intellectual debate on the concept of minjian religion and presents the relationship between state power and the religious revival in contemporary Chinese society. It then draws on fieldwork data to examine the hybrid nature of Chinese minjian religion from three aspects: the diversification of participants, the performative hybridisation of rituals, and the blending of spatial layouts. The main argument is that the revival of minjian religion involves the hybridisation of mystical and secular elements and of traditional and modern elements through the complex interactions between rural communities and official authorities.
Psychedelic Mystical Experience: A New Agenda for Theology
Authors: Cole-Turner Ron
Published: April 2022

When the link between psychedelic drugs and mystical states of experience was first discovered in the 1960s, Huston Smith challenged scholars in religion and philosophy to consider the implications. Very few took up his challenge. Beginning in 2006, hundreds of studies have linked psychedelics not just to mystical states of experience but to potential treatments for many mental health disorders. Regulatory approval for therapies is on the horizon, and hundreds of millions of people worldwide could be treated. Research findings challenge the underlying rationale of the War on Drugs, leading to decriminalization of specific psychedelic drugs or to authorization of their use in mental health contexts. Religious institutions are slowly adapting, with some referring to psychedelics as sacraments or as pathways to deeper spirituality. Religious leaders are also beginning to speak out publicly in support of careful use of these drugs, and some are training to become “psychedelic chaplains” to work alongside mental health professionals administering these drugs. Scholars in theology and religion are encouraged to engage these trends, to explore challenging philosophical and theological issues surrounding mystical states of experience in general, and to consider the long-term cultural impact of the most recent psychedelic research.
Quantitative-Bibliometric Study on Religiosity in the Last 25 Years of Social Science Research
Authors: Azancot-Chocrón David , López-Cordero Rafael , Úbeda-Sánchez Álvaro Manuel , Olmos-Gómez María del Carmen
Published: April 2022

Using a quantitative–bibliometric methodology, this study attempted to locate from which perspectives the study of religiosity is being approached in the scientific world, in order to achieve traceability for recent research using the following keywords—religiosity, gender, age, ethnicity and social life—locating possible future directions as well as fields of study yet to be discovered, and studying the evolution of scientific research on religiosity in the social sciences in the last 25 years. According to the results obtained in the Scopus database from the literature on concepts such as family, culture, spirituality, identity, marriage and sexuality, we discovered that the research revolved around six main components: education, mental health, attitudes, psychological aspects, religion and gender.
Water Spirits of the Yangzi River and Imperial Power in Traditional China
Authors: Yang Hua
Published: April 2022

Most research on the water spirits of the Yangzi has focused on popular worship and paid little attention to the Confucian discourse and its major role in establishing imperial legitimacy. Yet it is a crucial aspect to understand traditional politics in China. The water spirits of the Yangzi River and its tributaries and lakes were venerated, offered imperial sacrifices, and incorporated into codes of state ritual in traditional China. The canonized sacrifices to the water spirits of the Yangzi River basin symbolized the religious–political legitimacy of the imperial regimes. When an imperial court offered sacrifice to the water spirits of the Yangzi River basin incorporated by previous dynasties, this action demonstrated that the current court directly connected to past regimes and inherited the authority of sacrifice passed down from the ancient and the orthodox tradition of Confucian ritual classics. Since the majority of dynasty capitals in traditional China were located in the north with fewer rivers, worshipping water spirits of the Yangzi River basin would imply recognition and blessing from southern divinities. The practice of granting noble titles and temple plaques to those water spirits would further demonstrate the imperial courts’ control over the divine power. By communicating with and managing the water spirits of the Yangzi River, the imperial courts would also symbolize their political and military administration over the south and they are united, rather than divided, regimes.
The Strange Cult of Queen Dagmar
Authors: Sands Tracey R.
Published: April 2022

In 1205, the Danish king Valdemar II married a Bohemian princess, known in her new country as Dagmar. Little contemporary information exists concerning this queen, who died only seven years after her arrival. Nonetheless, Dagmar is one of very few figures from medieval Danish history whose names are familiar to a general Danish public in the present. Over the centuries, a narrative of her life has emerged, based largely on a group of ballad texts first written down in the sixteenth century, that Queen Dagmar was so exceptionally beautiful and kind that Danes (particularly common people) remained devoted to her memory through the generations. Moreover, several texts, and a remarkable early twentieth-century painting in St Bendt’s Church in Ringsted posit her as an intercessor on behalf of Denmark, in ways that come very close to portraying her as a saint, so much that one twentieth-century ballad scholar concludes that the Benedictine monks of Ringsted launched a canonization process on her behalf. This article investigates the image of Queen Dagmar as it has developed over the centuries with a particular eye toward implications or claims of sanctity, toward Dagmar’s purported role as an intercessor during and after her lifetime, and her perceived (and at times seemingly prescribed) role in the constitution of Danish identity.
Being Nonreligious in Croatia: Managing Belonging and Non-Belonging
Authors: Hazdovac Bajić Nikolina
Published: April 2022

Catholicism in the Croatian context has been one of the most powerful sources of collective belonging for centuries. Since the fall of socialism, desecularization tendencies have manifested as homogenization, collectivization, and deprivatization of religion. (Non)religiosity became a contested issue, which not only implied belonging (ethnic, national, historical) but was also highly politicized. This paper aims to explore how living in a society with a dominant collective religion influences the experience of nonreligious people. The conducted research was based on 30 semi-structured interviews with people who self-identify as nonreligious, but at the same time are not members of nonreligious organizations. The obtained data show that some elements of collectivism can push individuals away from religion, but for some nonreligious people, religiosity remains an important identification framework. Keeping a connection with religion is achieved through conformist behaviors or “cherry-picking” elements of religiosity, which are then combined in individually-consistent worldviews. Nonreligious people sometimes feel “left out” and experience their nonreligiosity as lonely and isolating, which they often do not want to pass on to others. This creates a specific position for some nonreligious individuals that is simultaneously “in” and “out” of religion, and challenges the way nonreligiosity is often imagined.
Security Threats in Intelligent Transportation Systems and Their Risk Levels
Authors: Zeddini Besma , Maachaoui Mohamed , Inedjaren Youssef
Published: April 2022

Intelligent Transport Systems (ITSs) are part of road transportation sector evolution and constitute one of the main steps towards vehicle automation. These systems use technologies that allow vehicles to communicate with each other or with road infrastructure. By increasing information quality and reliability, ITSs can improve road safety and traffic efficiency, but only if cybersecurity and data protection is ensured. With the increase in the number of cyberattacks around the world, cybersecurity is receiving increased attention, especially in the area of transportation security. However, it is equally important to examine and analyze security in depth when it concerns connected vehicles. In this paper, we propose a qualitative risk analysis of ITSs based on Threat, Risk, Vulnerability Analysis (TVRA) methodology, and we focus on ETSI ITS communication architecture. We present a review of solutions and countermeasures for identified critical attacks.
A Modified Two-Steps Three-Stage Inversion Algorithm for Forest Height Inversion Using Single-Baseline L-Band PolInSAR Data
Authors: Zhang Jianshuang , Zhang Yangjian , Fan Wenyi , He Liyuan , Yu Ying , Mao Xuegang
Published: April 2022

Forest height inversion with Polarimetric SAR Interferometry (PolInSAR) has become a research hotspot in the field of radar remote sensing. In this paper, we systematically studied a modified two-step, three-stage inversion simulating the L-band (L = 23 cm) full-polarization interferometric SAR data with an average forest height of 18 m using ESA PolSARpro-SIM software. We applied this method to E-SAR L-band single-baseline full PolInSAR data in 2003. In the first step, we modified the three-stage inversion algorithm based on phase diversity (PD)/maximum coherence difference (MCD) coherence optimization methods, corresponding to PD, MCD, respectively. In the second step, we introduced the coherence amplitude inversion term and modified the fixed weight to the variable of ε times the ground scattering ratio, which improved the accuracy of forest height inversion. The mean of forest height inversion by the HV method was the lowest (15.83 m) and the RMSE was the largest (4.80 m). The PD method was superior to the HV method with RMSE (4.60 m). The MCD method was slightly better than using the PD method with the smallest RMSE (4.43 m). After adding the coherence amplitude term, the RMSE was improved by 0.15 m, 0.14 m, and 0.08 m, respectively. The smallest RMSE was obtained by MCD, followed by the PD and HV methods. Although the robustness of the forest height inversion algorithm was reduced, the underestimation was improved and the RMSE was reduced. Due to the complexity of the real SAR E-SAR L-band single-baseline full PolInSAR data and the small sample sizes, the three-stage inversion methods based on coherent optimization were lower than the three-stage in-version method. After introducing the coherent magnitude term, the overestimation of the forest height was significantly weakened in HVWeight, PDweight, and MCDWeight, and PDWeight was optimal. The modified two-step, three-stage inversion algorithm had significant effects in alleviating forest height underestimation and overestimation, improving the accuracy of forest height inversion, and laying a foundation for the upcoming L-band SAR satellite generation, new SAR and LIDAR systems combined with RPAs (remotely piloted aircrafts)/UAVs (unmanned aerial vehicles) for small areas mapping initiatives, and promoting the depth and breadth of the SAR applications of the new SAR system.
Consistency of Vertical Reflectivity Profiles and Echo-Top Heights between Spaceborne Radars Onboard TRMM and GPM
Authors: Ji Lei , Xu Weixin , Chen Haonan , Liu Nana
Published: April 2022

Globally consistent long-term radar measurements are imperative for understanding the global climatology and potential trends of convection. This study investigates the consistency of vertical profiles of reflectivity (VPR) and 20-dBZ echo-top height (Topht20) between the two precipitation radars onboard the Tropical Rainfall Measuring Mission (TRMM) and Global Precipitation Measurement (GPM) satellites. Results show that VPR coincidently observed by the TRMM’s and GPM’s Ku-band radar agree well for both convective and stratiform precipitation, although certain discrepancies exist in the VPR of weak convection. Topht20s of the TRMM and GPM are consistent either for coincident events, or latitudinal mean during the 7-month common period, all with biases within the radar range resolution (0.1–0.2 km). The largest difference in the Topht20 between the TRMM’s and GPM’s Ku-band radar occurs in shallow precipitation. Possible reasons for this discrepancy are discussed, including sidelobe clutter, beam-mismatch, non-uniform beam filling, and insufficient sampling. Finally, a 23-year (1998–2020) climatology of Topht20 has been constructed from the two spaceborne radars, and the global mean Topht20 time series shows no significant trend in convective depth during the last two decades.
Distinguishing Algal Blooms from Aquatic Vegetation in Chinese Lakes Using Sentinel 2 Image
Authors: Pu Jing , Song Kaishan , Lv Yunfeng , Liu Ge , Fang Chong , Hou Junbin , Wen Zhidan
Published: April 2022

Algal blooms frequently occur in numerous lakes in China, risking human health and the environment. In contrast, aquatic vegetation contributes to water purification. Due to the similar spectral characteristics shared by algal and aquatic vegetation, both are hardly distinguishable in remote sensing imaging, especially in turbid water bodies. To address this challenge, this study constructed a method to effectively extract algal blooms and aquatic vegetation from the turbid water bodies using Sentinel 2 images with high spatial resolution. Our results showed that the accuracy of the extraction of vegetation information could reach 96.1%. Since this method combined the vegetation extraction results from multiple indices, it effectively tackled the mis-extraction when only the Floating Algae Index (FAI) or the Normalized Difference Vegetation Index (NDVI) is used in water with high turbidity. By combining the image time series information with the natural phenological characteristics of the aquatic vegetation and algal blooms, an improved Vegetation Presence Frequency (VPF) was developed. It effectively distinguished algal blooms and aquatic vegetation without actual measurement data. Based on the above method and process, the information of algal blooms and aquatic vegetation was sufficiently distinguished in five typical lakes in China (Lake Hulun, Lake Hongze, Lake Chaohu, Lake Taihu, and Lake Dianchi), and the spatial distribution was reasonably mapped. The overall identification accuracy of aquatic vegetation and algal blooms using the improved VPF ranged 71.8–84.3%. The spatial transferability test of the method in the independent lakes with the various optical properties indicated the prospects of its application in other turbid water bodies. This study should provide strong methodological and theoretical support for future monitoring of algal blooms in turbid water bodies with vigorous aquatic vegetation, especially in the absence of actual measurement data. This should have practical relevance for water environment management and governance departments.
Performance of Fingerprinting-Based Indoor Positioning with Measured and Simulated RSSI Reference Maps
Authors: Kawecki Robert , Hausman Sławomir , Korbel Piotr
Published: April 2022

Numerous indoor positioning technologies and systems have been proposed to localize people and objects in large buildings. Wi-Fi and Bluetooth positioning systems using fingerprinting have gained popularity, due to the wide availability of existing infrastructure. Unfortunately, the implementation of fingerprinting-based methods requires time-consuming radio surveys to prepare databases (RSSI maps) that serve as a reference for the radio signal. These surveys must be conducted for each individual building. Here, we investigate the possibility of using simulated RSSI maps with fingerprinting-based indoor localization systems. We discuss the suitability of the two popular radio wave propagation models for the preparation of RSSI reference data: ray tracing and multiwall. Based on an analysis of several representative indoor scenarios, we evaluated the performance of RSSI distribution maps obtained from simulations versus maps obtained from measurement campaigns. An experimental positioning system developed by the authors was used in the study. Based on Bluetooth Low Energy beacons and mobile devices (smartphones), the system uses fingerprinting followed by a particle filter algorithm to estimate the user’s current position from RSSI measurements and a reference spatial RSSI distribution database for each Bluetooth beacon in the building. The novelty of our contribution is that we evaluate the performance of the positioning system with RSSI maps prepared both from measurements and using the two most representative indoor propagation methods, in three different environments in terms of structure and size. We compared not only the three RSSI maps, but also how they influence the performance of the fingerprint-based positioning algorithm. Our original findings have important implications for the development of indoor localization systems and may reduce deployment times by replacing reference measurements with computer simulations. Replacing the labor-intensive and time-consuming process of building reference maps with computer modeling may significantly increase their usefulness and ease of adaptation in real indoor environments.
Winter Wheat Yield Estimation Based on Optimal Weighted Vegetation Index and BHT-ARIMA Model
Authors: Deng Qiuzhuo , Wu Mengxuan , Zhang Haiyang , Cui Yuntian , Li Minzan , Zhang Yao
Published: April 2022

This study aims to use remote sensing (RS) time-series data to explore the intrinsic relationship between crop growth and yield formation at different fertility stages and construct a high-precision winter wheat yield estimation model applicable to short time-series RS data. Sentinel-2 images were acquired in this study at six key phenological stages (rejuvenation stage, rising stage, jointing stage, heading stage, filling stage, filling-maturity stage) of winter wheat growth, and various vegetation indexes (VIs) at different fertility stages were calculated. Based on the characteristics of yield data continuity, the RReliefF algorithm was introduced to filter the optimal vegetation index combinations suitable for the yield estimation of winter wheat for all fertility stages. The Absolutely Objective Improved Analytic Hierarchy Process (AOIAHP) was innovatively proposed to determine the proportional contribution of crop growth to yield formation in six different phenological stages. The selected VIs consisting of MTCI(RE2), EVI, REP, MTCI(RE1), RECI(RE1), NDVI(RE1), NDVI(RE3), NDVI(RE2), NDVI, and MSAVI were then fused with the weights of different fertility periods to obtain time-series weighted data. For the characteristics of short time length and a small number of sequences of RS time-series data in yield estimation, this study applied the multiplexed delayed embedding transformation (MDT) technique to realize the data augmentation of the original short time series. Tucker decomposition was performed on the block Hankel tensor (BHT) obtained after MDT enhancement, and the core tensor was extracted while preserving the intrinsic connection of the time-series data. Finally, the resulting multidimensional core tensor was trained with the Autoregressive Integrated Moving Average (ARIMA) model to obtain the BHT-ARIMA model for wheat yield estimation. Compared to the performance of the BHT-ARIMA model with unweighted time-series data as input, the weighted time-series input significantly improves yield estimation accuracy. The coefficients of determination (R2) were improved from 0.325 to 0.583. The root mean square error (RMSE) decreased from 492.990 to 323.637 kg/ha, the mean absolute error (MAE) dropped from 350.625 to 255.954, and the mean absolute percentage error (MAPE) decreased from 4.332% to 3.186%. Besides, BHT-ARMA and BHT-CNN models were also used to compare with BHT-ARIMA. The results indicated that the BHT-ARIMA model still had the best yield prediction accuracy. The proposed method of this study will provide fast and accurate guidance for crop yield estimation and will be of great value for the processing and application of time-series RS data.
Field Data Collection Methods Strongly Affect Satellite-Based Crop Yield Estimation
Authors: Tiedeman Kate , Chamberlin Jordan , Kosmowski Frédéric , Ayalew Hailemariam , Sida Tesfaye , Hijmans Robert J.
Published: April 2022

Crop yield estimation from satellite data requires field observations to fit and evaluate predictive models. However, it is not clear how much field data collection methods matter for predictive performance. To evaluate this, we used maize yield estimates obtained with seven field methods (two farmer estimates, two point transects, and three crop cut methods) and the “true yield” measured from a full-field harvest for 196 fields in three districts in Ethiopia in 2019. We used a combination of nine vegetation indices and five temporal aggregation methods for the growing season from Sentinel-2 SR data as yield predictors in the linear regression and Random Forest models. Crop-cut-based models had the highest model fit and accuracy, similar to that of full-field-harvest-based models. When the farmer estimates were used as the training data, the prediction gain was negligible, indicating very little advantage to using remote sensing to predict yield when the training data quality is low. Our results suggest that remote sensing models to estimate crop yield should be fit with data from crop cuts or comparable high-quality measurements, which give better prediction results than low-quality training data sets, even when much larger numbers of such observations are available.
Fusion of a Static and Dynamic Convolutional Neural Network for Multiview 3D Point Cloud Classification
Authors: Wang Wenju , Zhou Haoran , Chen Gang , Wang Xiaolin
Published: April 2022

Three-dimensional (3D) point cloud classification methods based on deep learning have good classification performance; however, they adapt poorly to diverse datasets and their classification accuracy must be improved. Therefore, FSDCNet, a neural network model based on the fusion of static and dynamic convolution, is proposed and applied for multiview 3D point cloud classification in this paper. FSDCNet devises a view selection method with fixed and random viewpoints, which effectively avoids the overfitting caused by the traditional fixed viewpoint. A local feature extraction operator of dynamic and static convolution adaptive weight fusion was designed to improve the model’s adaptability to different types of datasets. To address the problems of large parameters and high computational complexity associated with the current methods of dynamic convolution, a lightweight and adaptive dynamic convolution operator was developed. In addition, FSDCNet builds a global attention pooling, integrating the most crucial information on different view features to the greatest extent. Due to these characteristics, FSDCNet is more adaptable, can extract more fine-grained detailed information, and can improve the classification accuracy of point cloud data. The proposed method was applied to the ModelNet40 and Sydney Urban Objects datasets. In these experiments, FSDCNet outperformed its counterparts, achieving state-of-the-art point cloud classification accuracy. For the ModelNet40 dataset, the overall accuracy (OA) and average accuracy (AA) of FSDCNet in a single view reached 93.8% and 91.2%, respectively, which were superior to those values for many other methods using 6 and 12 views. FSDCNet obtained the best results for 6 and 12 views, achieving 94.6%, 93.3%, 95.3%, and 93.6% in OA and AA metrics, respectively. For the Sydney Urban Objects dataset, FSDCNet achieved an OA and F1 score of 81.2% and 80.1% in a single view, respectively, which were higher than most of the compared methods. In 6 and 12 views, FSDCNet reached an OA of 85.3% and 83.6% and an F1 score of 85.5% and 83.7%, respectively.
Evaluation of a One-Dimensional Convolution Neural Network for Chlorophyll Content Estimation Using a Compact Spectrometer
Authors: Nofrizal Adenan Yandra , Sonobe Rei , Yamashita Hiroto , Seki Haruyuki , Mihara Harumi , Morita Akio , Ikka Takashi
Published: April 2022

Leaf chlorophyll content is used as a major indicator of plant stress and growth, and hyperspectral remote sensing is frequently used to monitor the chlorophyll content. Hyperspectral reflectance has been used to evaluate vegetation properties such as pigment content, plant structure and physiological features using portable spectroradiometers. However, the prices of these devices have not yet decreased to consumer-affordable levels, which prevents widespread use. In this study, a system based on a cost-effective fingertip-sized spectrometer (Colorcompass-LF, a total price for the proposed solution was approximately 1600 USD) was evaluated for its ability to estimate the chlorophyll contents of radish and wasabi leaves and was compared with the Analytical Spectral Devices FieldSpec4. The chlorophyll contents per leaf area (cm2) of radish were generally higher than those of wasabi and ranged from 42.20 to 94.39 μg/cm2 and 11.39 to 40.40 μg/cm2 for radish and wasabi, respectively. The chlorophyll content was estimated using regression models based on a one-dimensional convolutional neural network (1D-CNN) that was generated after the original reflectance from the spectrometer measurements was de-noised. The results from an independent validation dataset confirmed the good performance of the Colorcompass-LF after spectral correction using a second-degree polynomial, and very similar estimation accuracies were obtained for the measurements from the FieldSpec4. The coefficients of determination of the regression models based on 1D-CNN were almost same (with R2 = 0.94) and the ratios of performance to deviation based on reflectance after spectral correction using a second-degree polynomial for the Colorcompass-LF and the FieldSpec4 were 4.31 and 4.33, respectively.
Development of Chaos Terrain as Subaqueous Slide Blocks in Galilaei Crater, Mars
Authors: Nizam Nabila , Divola Claire , Day Mackenzie , Yin An , Moon Seulgi
Published: April 2022

Chaos terrain, expressed as enigmatic blocky landscapes on Mars, has poorly understood origins. Several hypotheses have been put forward to explain chaos terrain formation, but none fully account for the morphologies observed in Galilaei crater, the focus of this study. Previously inferred to be a paleolake, Galilaei crater hosts chaos terrain composed of kilometer-scale, disorganized blocks around the southern and southeastern margin of the crater. Blocks are concentrated near the base of the crater wall, with blocks of decreasing size extending into the crater interior. The crater wall slope in regions where these chaos blocks are present is notably lower than in regions where blocks are absent. Based on the observed morphologies, we propose the chaos terrain in Galilaei crater formed by gravity-driven slope failure and down-slope transport as subaqueous landslides and mass flows, initiated at a time when the paleolake level was still high. We propose and discuss Earth analogs for the observed terrain and use mapping-constrained spatiotemporal relationships to reconstruct the sequence of landform development. Subaqueous landslides represent an uncommonly invoked mechanism to explain chaos terrain on Mars, reinforcing the idea that one mechanism cannot explain the diversity of this enigmatic terrain.
Evaluating Vertical Accuracies of Open-Source Digital Elevation Models over Multiple Sites in China Using GPS Control Points
Authors: Liu Xiangping , Ran Mengying , Xia Huimin , Deng Mingjun
Published: April 2022

Digital elevation models (DEMs) are widely used across a range of fields. Several open-source global DEMs have been released, including the advanced land observing satellite world 3D 30 m DEM (AW3D30DEM), advanced spaceborne thermal emission and reflection radiometer global DEM (ASTER GDEM), shuttle radar topography mission DEM (SRTMDEM), and TerraSAR-X for digital elevation measurement (TanDEM-X). ASTER and SRTM are the most widely used DEMs, while the newer models AW3D30DEM and TanDEM-X are becoming increasingly popular. Many studies have evaluated the qualities of these DEMs; however, few multi-regional studies have been conducted in China. To comprehensively and systematically evaluate the qualities of these DEMs in China, the vertical accuracies of AW3D, ASTER, STRM (all 30 m), and TanDEM-X (90 m) were tested across 16 regions in China. Using high-precision global positioning system control points for reference, error values were determined by subtracting these reference values from corresponding global DEM elevation values. As the study only covered flat areas (slope < 5°), slope was treated as a controlled variable. After assessing the impacts of the slope aspect and land cover type, variations in vertical accuracy were examined with respect to longitude and latitude. Overall, TanDEM-X exhibited the highest stability and accuracy, AW3D30 and SRTM also performed well, while ASTER exhibited the worst accuracy. The DEMs showed relationships with the slope aspect and land cover type, assuming that slope had no influence on vertical accuracy. In general, vertical accuracy in high latitudes was slightly better than that in low latitudes, and no evident variations were observed with respect to longitude. This study is the first to conduct DEM analysis across many regions in China from open sources. Since most of the users rely on public domain DEM datasets, this work contributes to their analysis in academic and engineering fields.
A Numerical Investigation of the Dispersion Law of Materials by Means of Multi-Length TDR Data
Authors: Persico Raffaele , Farhat Iman , Farrugia Lourdes , Sammut Charles
Published: April 2022

In this paper, we propose a method for retrieving the dispersion law of a material under test from multi-length TDR measurements in reflection mode, repeated at several frequencies. By replacing the multi-frequency measurements with measurements using multi-length TDR probe, it is possible to retrieve the complex equivalent permittivity of the material in a frequency band of interest. The proposed procedure does not require a priori knowledge of the type of dispersion law of the material, which instead can possibly be inferred from the measured data. The algorithm is validated using numerically simulated data obtained with the commercial code CST Microstudio®.
Fast Displacement Estimation of Multiple Close Targets with MIMO Radar and MUSICAPES Method
Authors: Wang Jian , Wang Yuming , Li Yueli , Huang Xiaotao
Published: April 2022

Interferometric radar is a hot research topic in manmade target displacement measuring applications, as it features high precision, a large operation range, and a remote multiple point measuring ability. Most one-dimensional interferometric radars use single-input single-output (SISO) radar architecture to achieve a high repetition measuring rate of more than 200 Hz; however, it cannot resolve multiple targets with the same radial range but different azimuth angles. This paper presents a multiple-input multiple-output (MIMO) radar that adopts a limited number of antennas (usually tens) to simultaneously improve azimuth resolution and achieve a high repetition measuring rate. A MUSICAPES algorithm is proposed, which is cascades the multiple signal classification (MUSIC) algorithm and the amplitude and phase estimation (APES) filter. The MUSIC algorithm is used to further improve the angular resolution of the small array. The APES is used to precisely recover the phases of the multiple close targets by suppressing their mutual interferences. Simulations and experiments with a millimeter-wave radar validate the performance of the proposed method.