bluuebunny/crossref_metadata_2025 huggingface dataset:
Carboxymethyl Cellulose/Zn-Organic Framework Down-Regulates Proliferation and Up-Regulates Apoptosis and DNA Damage in Colon and Lung Cancer Cell Lines
Authors: Negm Amr , Gouda Mohamed , Ibrahim Hairul-Islam M.
Published: May 2022

A solvothermal technique was used to prepare a Zn–benzenetricarboxylic acid (Zn@BTC) organic framework covered with a carboxymethyl cellulose (CMC/Zn@BTC). Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), and Brunauer, Emmett, and Teller (BET) surface area were applied to characterize CMC/Zn@BTC. Moreover, the anticancer, anti-migrative, anti-invasive, and anti-proliferative action of CMC/Zn@BTC nanoparticles were assessed on cancer cell lines. Apoptotic markers and DNA damage were assessed to explore the cellular and biological changes induced by CMC/Zn@BTC nanoparticles. The microscopic observation revealed that CMC controls the surface morphology and surface characteristics of the Zn@BTC. The obtained BET data revealed that the Zn@BTC nanocomposite surface area lowers from 1061 m2/g to 740 m2/g, and the pore volume decreases from 0.50 cm3/g to 0.37 cm3/g when CMC is applied to Zn@BTC nanocomposites. The cellular growth of DLD1 and A549 was suppressed by CMC/Zn@BTC, with IC50 values of 19.1 and 23.1 μg/mL, respectively. P53 expression was upregulated, and Bcl-2 expression was downregulated by CMC/Zn@BTC, which promoted the apoptotic process. Furthermore, CMC/Zn@BTC caused DNA damage in both cancer cell lines with diverse impact, 66 percent (A549) and 20 percent (DLD1) compared to cisplatin’s 52 percent reduction. CMC/Zn@BTC has anti-invasive properties and significantly reduced cellular migration. Moreover, CMC/Zn@BTC aims key proteins associated with metastasis, proliferation and programmed cellular death.
Using Gas Counter Pressure and Combined Technologies for Microcellular Injection Molding of Thermoplastic Polyurethane to Achieve High Foaming Qualities and Weight Reduction
Authors: Chen Shia-Chung , Lee Kuan-Hua , Chang Che-Wei , Hsu Tzu-Jeng , Feng Ching-Te
Published: May 2022

Microcellular injection molding technology (MuCell®) using supercritical fluid (SCF) as a foaming agent offers many advantages, such as material and energy savings, low cycle time, cost-effectiveness, and the dimensional stability of products. MuCell® has attracted great attention for applications in the automotive, packaging, sporting goods, and electrical parts industries. In view of the environmental issues, the shoe industry, particularly for midsole parts, is also seriously considering using physical foaming to replace the chemical foaming process. MuCell® is thus becoming one potential processing candidate. Thermoplastic polyurethane (TPU) is a common material for molding the outsole of shoes because of its outstanding properties such as hardness, abrasion resistance, and elasticity. Although many shoe manufacturers have tried applying Mucell® processes to TPU midsoles, the main problem remaining to be overcome is the non-uniformity of the foaming cell size in the molded midsole. In this study, the MuCell® process combined with gas counter pressure (GCP) technology and dynamic mold temperature control (DMTC) were carried out for TPU molding. The influence of various molding parameters including SCF dosage, injection speed, mold temperature, gas counter pressure, and gas holding time on the foaming cell size and the associated size distribution under a target weight reduction of 60% were investigated in detail. Compared with the conventional MuCell® process, the implementation of GCP technology or DMTC led to significant improvement in foaming cell size reduction and size uniformity. Further improvement could be achieved by the simultaneous combination of GCP with DMT, and the resulting cell density was about fifty times higher. The successful possibility for the microcellular injection molding of TPU shoe midsoles is greatly enhanced.
Supercritical CO2 Foaming of Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)
Authors: Zhang Tao , Jang Yunjae , Lee Eunhye , Shin Sooan , Kang Ho-Jong
Published: May 2022

The supercritical carbon dioxide foaming characteristics of the biodegradable polymer poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)) are studied for environmentally friendly packaging materials. The effect of the 4HB composition of the P(3HB-co-4HB) copolymers on the foaming conditions such as pressure and temperature is studied and the density and the expansion ratio of the resulting P(3HB-co-4HB) foam are together evaluated. The increase in the 4HB content reduces the crystallinity and tan δ value of P(3HB-co-4HB) required for the growth of the foam cells. Therefore, the foaming temperature needs to be lower to retain a suitable tan δ value of P(3HB-co-4HB) for foaming. It was found that P(3HB-co-4HB) with less crystallinity showed better formability and cell uniformity. However, foaming is not possible regardless of the foaming temperature when the 4HB content of P(3HB-co-4HB) is over 50%, due to the high tan δ value. A lower foam density and higher expansion ratio can be obtained with crystalline P(3HB-co-4HB) of low 4HB content, compared with non-crystalline P(3HB-co-4HB) of high 4HB content. The expansion ratio of P(3HB-co-4HB) foams can be increased slightly by using a chain extender, due to the lowing of crystallinity and tan δ. This is most effective in the case of P(3HB-co-4HB), whose 4HB content is 16%.
Sensors and Sensor Fusion Methodologies for Indoor Odometry: A Review
Authors: Yang Mengshen , Sun Xu , Jia Fuhua , Rushworth Adam , Dong Xin , Zhang Sheng , Fang Zaojun , Yang Guilin , Liu Bingjian
Published: May 2022

Although Global Navigation Satellite Systems (GNSSs) generally provide adequate accuracy for outdoor localization, this is not the case for indoor environments, due to signal obstruction. Therefore, a self-contained localization scheme is beneficial under such circumstances. Modern sensors and algorithms endow moving robots with the capability to perceive their environment, and enable the deployment of novel localization schemes, such as odometry, or Simultaneous Localization and Mapping (SLAM). The former focuses on incremental localization, while the latter stores an interpretable map of the environment concurrently. In this context, this paper conducts a comprehensive review of sensor modalities, including Inertial Measurement Units (IMUs), Light Detection and Ranging (LiDAR), radio detection and ranging (radar), and cameras, as well as applications of polymers in these sensors, for indoor odometry. Furthermore, analysis and discussion of the algorithms and the fusion frameworks for pose estimation and odometry with these sensors are performed. Therefore, this paper straightens the pathway of indoor odometry from principle to application. Finally, some future prospects are discussed.
Synthesis of Coumarin Derivatives: A New Class of Coumarin-Based G Protein-Coupled Receptor Activators and Inhibitors
Authors: Fu Zhe , Zhang Linjie , Hang Sijin , Wang Shiyi , Li Na , Sun Xiaojing , Wang Zian , Sheng Ruilong , Wang Fang , Wu Wenhui , Guo Ruihua
Published: May 2022

To expand the range of daphnetin-based inhibitors/activators used for targeting G protein-coupled receptors (GPCRs) in disease treatment, twenty-five coumarin derivatives 1–25, including 7,8-dihydroxycoumarin and 7-hydroxycoumarin derivatives with various substitution patterns/groups at C3-/4- positions, were synthesized via mild Pechmann condensation and hydroxyl modification. The structures were characterized by 1H NMR, 13C NMR and ESI-MS. Their inhibition or activation activities relative to GPCRs were evaluated by double-antibody sandwich ELISA (DAS–ELISA) in vitro. The results showed that most of the coumarin derivatives possessed a moderate GPCR activation or inhibitory potency. Among them, derivatives 14, 17, 18, and 21 showed a remarkable GPCR activation potency, with EC50 values of 0.03, 0.03, 0.03, and 0.02 nM, respectively. Meanwhile, derivatives 4, 7, and 23 had significant GPCR inhibitory potencies against GPCRs with IC50 values of 0.15, 0.02, and 0.76 nM, respectively. Notably, the acylation of hydroxyl groups at the C-7 and C-8 positions of 7,8-dihydroxycoumarin skeleton or the etherification of the hydroxyl group at the C-7 position of the 7-hydroxycoumarin skeleton could successfully change GPCRs activators into inhibitors. This work demonstrated a simple and efficient approach to developing coumarin derivatives as remarkable GPCRs activators and inhibitors via molecular diversity-based synthesis.
Tech-Economic Assessment of Power Transmission Options for Large-Scale Offshore Wind Farms in China
Authors: Jiang Qin , Li Baohong , Liu Tianqi
Published: May 2022

China is taking initiative in energy transition to cope with the long-term controversy of its enormous energy consumption, aiming to use less carbon. Wind power, especially offshore wind energy, has become a prevailing alternative due to its low carbon emissions, renewability, competitiveness, and operation security. The layout of a transmission channel is a key consideration in marine project implementation. This paper investigates the technical characteristics, application status, and viable advantages of a conventional AC transmission, voltage source converter-based high-voltage direct current (VSC-HVDC) transmission, gas-insulated line (GIL) transmission, and hybrid HVDC transmission. A component-resolved evaluation model was proposed to estimate the costs to be incurred of four electrical transmission options for offshore wind power along the coast of Eastern China, with technical feasibility and economical considerations. Cost comparisons and component sensitivity analyses were developed with different transmission distances and capacities. Results suggest HVAC transmission and VSC-HVDC are the preferable solutions for present offshore wind farm development in Eastern China, and the economic potential of the hybrid HVDC makes it feasible for future deployment. Some conclusions can be applied in disparate regions across the globe.
Special Issue on “Soil and Sustainable Development: Challenges and Solutions”
Authors: Fernández-Calviño David , Arias-Estévez Manuel , Pereira Ruth , Lourenço Joana
Published: May 2022

Food production is increasing year by year, with modern agriculture occupying high-fertility soils [...]
Analysis of Grid Response Strategies for the Safety Behavior Risk Events of Transportation System Based on System Dynamics—“the Assistant Watchman Does Not Appear as Required”
Authors: Zhang Huafeng , Qi Changmao , Ma Mingyuan
Published: May 2022

Employees are the most important and dynamic elements in the railway transportation system. How to achieve accurate control of inertial violation of “key person, key matter, key period”, and formulate more personalized risk response strategy is a thorny problem that faced by safety managers. The existing risk response usually takes control measures from the perspective of the system as a whole, ignoring the heterogeneity of risk, and the selection of response strategies only considers the target risks to be dealt with, ignoring the secondary risks that may occur in the process of risk response, or the residual risks formed by changing the existing risk, coupled with the lack of quantitative evaluation of risk response effect, resulting in poor risk response effect. By introducing the grid theory and taking the risk event of “the assistant watchman does not appear as required” at Huangyangcheng station of Shenshuo Railway as an example, this study constructs a grid response model of the assistant watchman risk events based on system dynamics. Through the grid division, the model accurately locates and classifies the assistant watchman on duty. Then, during the system dynamics simulation process, the hazard factor is regarded as a bridge, and the traditional virtual boundary of system simulation is transformed into accurate grid definition. By improving the response strategy of safety behavior risk event of the assistant watchman on duty in cell grid and using Vensim-PLE software for personalized simulation, the intervention of “the assistant watchman does not appear as required” risk event is transformed from qualitative analysis to dynamic quantitative mathematical model, so as to realize the personalized response simulation analysis of employees in the grid.
Development of Evaluation Methods for Anti-Glycation Activity and Functional Ingredients Contained in Coriander and Fennel Seeds
Authors: Sawabe Akiyoshi , Yamashita Atsuyuki , Fujimatsu Mei , Takeda Ryuji
Published: May 2022

Spices are known to have various physiological functions. We focused on the anti-glycation effects of spices, researched anti-glycation active ingredients in coriander (Coriandrum sativum L.) and fennel (Foeniculum vulgare) seeds, and conducted experiments using human skin-derived fibroblast TIG-110 cells as a model of glycation. We isolated 11 compounds from two spice seeds and found several substances that showed anti-glycation activity. A new compound (5,5′-diallyl-2,2′-diglucopyranosyl-3,3′-dimethoxy diphenyl ether) was isolated from fennel seeds and showed high anti-glycation activity with an IC50 value of 0.08 mM, thereby indicating a high anti-glycosylation activity. In this study, we established a glyoxal (GO)-induced glycation test method for human skin cells, confirmed the anti-glycation effect of spice seeds using this glycation induction model, and found that the exposure of TIG-110 human skin-derived fibroblast cells to GO reduced cell viability. The most stable conditions for cell viability were found to be a GO concentration of 1.25 mM and a culture time of 48 h. We evaluated extracts and isolates of spice seeds using this model as a model test for glycation induction. We conducted qualitative and quantitative analyses of carboxymethyl lysine (CML), a type of AGE, to determine the relationship between cell viability and AGEs. The relationship between cell viability and the amount of CML was correlated. Establishing a glycation induction model test using skin cells makes it possible to quickly screen extracts of natural ingredients in the future. Moreover, the results of this model showed that extracts of two spice seeds and their isolates have high anti-glycation activity, and they are expected to be used as cosmetics, health foods, and pharmaceutical ingredients.
Subgingival Zone Detection via Reverse Subgingival Scan
Authors: Zingari Francesco , Meglioli Matteo , Gallo Francesco , Toffoli Andrea , Macaluso Guido Maria
Published: May 2022

An important issue with digital impression techniques is the difficulty in replicating the subgingival zone, particularly when abutments are prepared with a vertical finish line. We propose a novel procedure, the reverse subgingival scan (RSS), to depict the subgingival area via digital impression without a retraction cord or the distortion of the sulcus. The software workflow, beginning with a digital dental impression, was performed using Exocad® (Align Technology) and Meshmixer® (Autodesk). The approach is based on the direct alignment of the surface of abutments, which is used as a reference point. The efficacy of the RSS approach was confirmed via fit tests, radiographic control assessments, and evaluations of the rate of tissue compression of the final prosthetic restoration, so long as the provisional had a perfect fit. RSS yields information on the transversal dimension and depth of the gingival sulcus. The procedure depends on the quality and characteristics of the provisional restoration, and is suitable only for cases in which the finish line of the final crown is at the same level or more coronal than that of the provisional.
The Mediating Role of School and Sibling Bullying in the Relationship between Subjective Well-Being and Mental Health Symptoms
Authors: Katsantonis Ioannis
Published: May 2022

Recently, empirical studies have indicated an association between well-being and mental health. The nature of this association remains unclear since some studies suggest it is weak, whilst others indicate it is strong. The present study seeks to contribute to this dialogue by modelling not only the relationship between well-being and internalising and externalising mental health symptoms but also by introducing a mediation model where school and sibling bullying, as risk factors, are acting as mediators. A national sample of 1244 youth (Mage = 12.47, SD = 1.69) from the Understanding Society household panel study in the UK was utilised to estimate the structural equation model. The findings showed that the direct effect of well-being on internalising symptoms was negative and strong, whereas it was negative and moderate on externalising symptoms. Furthermore, the pattern of indirect effects from subjective well-being to internalising and externalising mental health symptoms displayed some differences in the level of statistical significance and strength. Implications for policy and practice are discussed.
Addiction and COVID: Issues, Challenges, and New Telehealth Approaches
Authors: Edinoff Amber N. , Kaufman Sarah E. , Chauncy Tyler M. , Erwin Abigail P. , Russo Katherine M. , Nelson Meredith E. , Cornett Elyse M. , Shah-Bruce Mila , Kaye Adam M. , Kaye Alan D.
Published: May 2022

In recent decades, the United States has seen a substantial increase in the number of people diagnosed with substance use disorder (SUD). Both SUDs and COVID-19 separately have had, and continue to have, a widespread impact on our society. While they are two distinct entities, they are intricately related and have been shown to influence one another. Lockdown mandates intended to enhance public safety produced unintended consequences for people with SUDs by decreasing access to treatment and disrupting their current care. Telehealth could offer a solution to this disruption as its utilization expands the provider’s reach and increases access to treatment in underserved populations, including those with SUDs. The use of telemedicine seems to result in higher rates of patient satisfaction, compliance, and treatment retention rates while maintaining the need for social distancing. Even when pandemic restrictions resolve, telehealth can continue to provide invaluable benefits to individuals with addiction, particularly those in rural America. In summary, ongoing research regarding telehealth delivery and the expansion of telehealth is a byproduct of the pandemic and can advance the American healthcare system beyond the days of COVID-19. This manuscript will review studies regarding the use of telehealth in SUD with the hope that further research within and beyond the COVID-19 pandemic will lead to the increased use of telehealth by those involved in and those receiving care for SUDs.
Excited about Receptors
Authors: Safe Stephen
Published: May 2022

Receptors are widely expressed in human tissues and play a key role in maintaining cellular homeostasis and in pathophysiology, and they are important drug targets for the treatment of human diseases [...]
How Does Buddhist Contemplative Space Facilitate the Practice of Mindfulness?
Authors: Chen Anran , Porter Nicole , Tang Yue
Published: May 2022

This paper examines the spaces where Buddhist spiritual activity—specifically mindfulness practice—takes place, exploring how contemporary urban Buddhist contemplative places may benefit people’s mindful experience. Historical Buddhist contemplative places are examined through a literature review of Buddhist philosophy and Buddhist architecture and landscape. A case study of Kagyu Samye Dzong London, UK (KSDL) in the contemporary western context is then presented, drawing upon mixed methods (qualitative spatial analysis, questionnaires with mindfulness practitioners, and an in-depth interview with the director of the Buddhist center). This study investigates the relationship between the Buddhist spiritual activity of mindfulness practice and one specific physical space, exploring how the KSDL has been designed and is used to facilitate such mindfulness awareness and insight. Results suggest that quiet, solitude, and the presence of nature are three tangible spatial qualities that can facilitate mindful practice to some extent. However, additional relational or intangible qualities, namely the presence of The Three Jewels and blessings, are equally if not more important when sustaining mindfulness for Buddhist practitioners, and these contemplative qualities are more than “spatial”. Both the physical tangible qualities and intangible qualities are indispensable in the contemplative space and in influencing one’s practice. Findings evidence the importance of physical design and space for supporting contemporary mindfulness practitioners, whilst acknowledging that mindfulness emanates from—and can ultimately be discovered from—within.
Alterity, Alacrity, and Excess: Continental Philosophical Interpretations of the Figure of Abraham According to Franz Rosenzweig, Emmanuel Levinas, Jacques Derrida and Jean-Luc Marion
Authors: Feldmann Kaye Miriam
Published: May 2022

I propose a new reading of a selection of continental philosophical interpretations of the nature of existentialism after the dialogical turn. This analysis will focus on the particular case study of the biblical character of Abraham as a case in point. Philosophical treatments thereof allow for a consideration of different but connected approaches through the study and re-readings of the character of Abraham, which begin with Kierkegaard’s well-known rendition of the sacrifice of Isaac. This study will focus on interpretations since Kierkegaard, with attention to the continental philosophical trend. The four thinkers I bring, all offered critiques, and even rejections of, a purely existential position. These positions are well-known in the field. However, Existentialism is never actually overcome despite these four critiques of Kierkegaard’s model of Abraham. I will demonstrate this through an analysis of the case of interpretations of the biblical figure of Abraham, showing the ways in which Kierkegaard remains present in dialogical philosophy and even deconstructionism. For Franz Rosenzweig, his stance is relational and thus is fascinated yet ambivalent towards the readiness of Abraham to sacrifice; Emmanuel Levinas admires Kierkegaard’s emphasis on the subject/ivity (Proper Names and Difficult Freedom); Jacques Derrida admires Abraham’s passion (Gift of Death and Abraham as Other); and for Jean-Luc Marion, Abraham’s sacrifice does not present a relinquishing of self, but rather, the phenomenological act symbolises returning a Gift.
Withered Wood and Dead Ashes—Making Sense of the Sacred Bodies of Kamatari at Tōnomine
Authors: Lomi Benedetta
Published: May 2022

The portrait statue of Fujiwara Kamatari (614–669) enshrined at Tōnomine is well known for its agency and mantic powers. Known to crack whenever the stability of the clan was under threat, the icon was carefully observed and cared for. However, not one but two portrait statues of the Fujiwara ancestor existed at Tōnomine in the Heian period, until one was destroyed in the infamous 1208 attack by armed supporters of Kinpusen. This article proposes first to investigate the relationship between these two icons, to show how their dynamic interaction is at the source of the cracking episodes that came to define Kamatari’s cult in later centuries. Then, by looking at the ways in which members of the Fujiwara clan reflected on the nature of the remains of the statue lost in 1208 and on the role of the extant one, it draws attention to how the ritualization of Kamatari’s statue was also couched in Confucian ideas and practices.
Buddhism and Martial Arts in Premodern Japan: New Observations from a Religious Historical Perspective
Authors: Trenson Steven
Published: May 2022

This article investigates two issues regarding the Buddhism of premodern Japanese martial arts. The first issue concerns the historical channels through which Buddhist elements were adopted into martial lineages, and the second pertains to the general character of the Buddhism that can be found in the various martial art initiation documents (densho). As for the first issue, while previous scholarship underscored Shugendō (mountain asceticism) as an important factor in the earliest phases of the integration process of Buddhist elements in martial schools, this study focuses on textual evidence that points to what is referred to as “medieval Shinto”—a Shinto tradition that heavily relied on Esoteric Buddhist (Mikkyō) teachings—in scholarship. Regarding the second issue, although numerous studies have already shown the indebtedness of premodern martial schools to Buddhist teachings drawn mainly from the Esoteric Buddhist or Zen traditions, this article sheds more light on the nature of these teachings by drawing attention to the fact that they often emphasize the Buddhist thought of isshin or “One Mind”. The article illustrates how this thought was adopted in premodern martial art texts and in doing so clarifies the reasons why Buddhism was valued in those arts.
American Muslim Attitudes toward Jews
Authors: Cohen Jeffrey E.
Published: May 2022

Muslims are often accused of being antisemitic and for being a major source of attacks and violence against Jews and Jewish institutions. Research also finds variation in Muslim orientations toward Jews at the aggregate, cross-national level, with lower levels of anti-Jewish sentiment in some western nations. There is also variation in the antisemitic sentiment of Muslims at the individual level in western nations. This paper asks whether factors that affect antisemitism among non-Muslims similarly affect Muslims with the same weight. In order to estimate these relative effects with precision, it is desirable to have a common dataset that includes both Muslims and non-Muslims. Since Muslims comprise a small percentage of the population in most western nations, nationally representative surveys rarely contain enough Muslim respondents for reliable statistical analysis. This paper uses the Democracy Fund + UCLA Nationscape survey, which has over 500,000 respondents, including 5000 Muslim respondents, sufficient for such analysis. The analysis finds that although American Muslims are less positive toward Jews than non-Muslims, the difference is not great, and, on average, American Muslims have positive views of Jews. Results also find that education, being foreign born, and perceiving discrimination against Muslims similarly affects Muslim and non-Muslim attitudes toward Jews. However, perceptions of a weak economy and age have discernably different effects on Muslim and non-Muslim attitudes toward Jews.
Trends and Opportunities of Bivalve Shells’ Waste Valorization in a Prospect of Circular Blue Bioeconomy
Authors: Summa Daniela , Lanzoni Mattia , Castaldelli Giuseppe , Fano Elisa , Tamburini Elena
Published: May 2022

Bivalves aquaculture is already considered a very sustainable for of food production and might become an essential pillar on which to develop future global food security. However, with the increase in production, a correspondingly great amount of waste will be produced all around the earth, principally in the form of shells, which can represent up to 90% of the fresh mollusk weight. Nowadays, shell waste has no notable use and is commonly regarded as waste, often dumped in landfill, or thrown back into the sea, causing a significant level of environmental concern, and resulting in a loss of natural and valuable resources. Bivalve shells are mainly formed by CaCO3, giving them the potential to become a promising secondary raw material for several applications, from a circular economy perspective. This paper aims to review the scientific literature of the last twenty years and the principal recent trends in shell waste reuse, describing applications that are already in place on a large scale in agriculture and livestock, soils, water and wastewater remediation, biodiesel production and biofilters, as well as niche applications that now simply have the potential to be scaled up.
Cat-Inspired Gaits for a Tilt-Rotor—From Symmetrical to Asymmetrical
Authors: Shen Zhe , Tsuchiya Takeshi
Published: May 2022

Among the tilt-rotors (quadrotors) developed in recent decades, Ryll’s model with eight inputs (four magnitudes of thrusts and four tilting angles) attracted great attention. Typical feedback linearization maneuvers all of the eight inputs with a united control rule to stabilize this tilt-rotor. Instead of assigning the tilting angles by the control rule, the recent research predetermines the tilting angles and leaves the magnitudes of thrusts with the only control signals. These tilting angles are designed to mimic the cat-trot gait while avoiding the singular decoupling matrix in feedback linearization. To complete the discussions of the cat-gait inspired tilt-rotor gaits, this research addresses the analyses on the rest of the common cat gaits, walk, run, transverse gallop, and rotary gallop. It is found that the singular decoupling matrix exists in walk gait, transverse gallop gait, and rotary gallop gait; the decoupling matrix can hardly be guaranteed to be invertible analytically. Further modifications (scaling) are conducted to these three gaits to accommodate the application of feedback linearization; the acceptable attitudes, leading to invertible decoupling matrix, for each scaled gait are evaluated in the roll-pitch diagram. The modified gaits with different periods are then applied to the tilt-rotor in tracking experiments, in which the references are uniform rectilinear motion and uniform circular motion with or without the equipment of the modified attitude-position decoupler. All the experiments are simulated in Simulink, MATLAB. The result shows that these gaits, after modifications, are feasible in tracking references, especially for the cases equipped with the modified attitude-position decoupler.
A Robotic Platform for Aircraft Composite Structure Inspection Using Thermography
Authors: Samarathunga Amalka Indupama , Piyasundara Neelanjana , Wanigasooriya Anuka Iroshan , Kumara Buddhika Sampath , Vithanage Vimukkthi Priyadarshana , Chathuranga Damith Suresh
Published: May 2022

Water ingression is a critical issue in honeycomb composite structures, which could result in catastrophic structural failure. In the aviation industry, they are widely used to manufacture critical aircraft structural components including fuselage, wings, and flight control surfaces. Catastrophic failure of these structures would be disastrous, thus identifying water accumulation in earlier stages of the defect is necessary. The conventional non-destructive testing method is thermography which is performed using handheld thermography cameras by manually accessing the specific areas. This method of inspection has been identified to be a risky, costly, time-consuming, and inspector-dependent technique. This paper describes using a wall-climbing robotic platform that can be controlled remotely to access and perform the inspection on a targeted structural area replacing the manual process. The designed wall-climbing inspection robot onboard a heat pump to stimulate the composite surface to an adequate temperature and, an infrared sensor to feed the real-time temperature data via Bluetooth serial communication to a remote computer system to be processed into a thermal image and evaluated to determine the presence of water. The results obtained from the thermographic sensor are validated with the comparison of the Fluke thermography camera.
Comparison between the Mesospheric Winds Observed by Two Collocated Meteor Radars at Low Latitudes
Authors: Zeng Jie , Yi Wen , Xue Xianghui , Reid Iain , Hao Xiaojing , Li Na , Chen Jinsong , Chen Tingdi , Dou Xiankang
Published: May 2022

This study compares the hourly mesospheric horizontal winds observed by two collocated and independent low-latitude meteor radars operating at 37.5 MHz and 53.1 MHz in Kunming, China (25.6°N, 103.8°E). Upon analyzing simultaneously detected meteor echoes, we find a fixed angular deviation between the baselines of the two meteor radar antenna arrays within the east–north–up coordinate system. Then, we correct the deviation in the antenna azimuth direction using a novel method and recalculate the horizontal zonal and meridional winds. A comparison of the results before and after the correction shows strong consistency between the winds observed by both meteor radars within the entire detection altitude range. Furthermore, we summarize the performance of different techniques for measuring mesospheric winds. Ultimately, our statistical analysis approach allows the uncertainties associated with meteor radar wind observations to be more precisely estimated.
Integrating Hybrid Pyramid Feature Fusion and Coordinate Attention for Effective Small Sample Hyperspectral Image Classification
Authors: Ding Chen , Chen Youfa , Li Runze , Wen Dushi , Xie Xiaoyan , Zhang Lei , Wei Wei , Zhang Yanning
Published: May 2022

In recent years, hyperspectral image (HSI) classification (HSIC) methods that use deep learning have proved to be effective. In particular, the utilization of convolutional neural networks (CNNs) has proved to be highly effective. However, some key issues need to be addressed when classifying hyperspectral images (HSIs), such as small samples, which can influence the generalization ability of the CNNs and the HSIC results. To address this problem, we present a new network that integrates hybrid pyramid feature fusion and coordinate attention for enhancing small sample HSI classification results. The innovative nature of this paper lies in three main areas. Firstly, a baseline network is designed. This is a simple hybrid 3D-2D CNN. Using this baseline network, more robust spectral-spatial feature information can be obtained from the HSI. Secondly, a hybrid pyramid feature fusion mechanism is used, meaning that the feature maps of different levels and scales can be effectively fused to enhance the feature extracted by the model. Finally, coordinate attention mechanisms are utilized in the network, which can not only adaptively capture the information of the spectral dimension, but also include the direction-aware and position sensitive information. By doing this, the proposed CNN structure can extract more useful HSI features and effectively be generalized to test samples. The proposed method was shown to obtain better results than several existing methods by experimenting on three public HSI datasets.
RETRACTED: Geometric Construction of Video Stereo Grid Space
Authors: Zhang Huangchuang , Shi Ruoping , Li Ge
Published: May 2022

The construction of digital twin cities is a current research hotspot. Video data are one of the important aspects of digital twin cities, and their digital modeling is one of the important foundations of its construction. For this reason, the construction and digital analysis of video data space has become an urgent problem to be solved. After in-depth research, this study found that the existing video space construction methods have three shortcomings: first, the problem of high requirements for objective conditions or low accuracy; second, the lack of easy and efficient mapping algorithms from 2D video pixel coordinates to 3D; and third, the lack of efficient correlation mechanisms between video space and external geographic information, making it difficult to integrate video space with external information, and thus prevent a more effective analysis. In view of the above problems, this paper proposes a video stereo grid geometric space construction method based on GeoSOT-3D stereo grid coding and a camera imaging model to form a video stereo grid space model. Finally, targeted experiments of video stereo grid space geometry construction were conducted to analyze the experimental results before and after optimization and compare the variance size to verify the feasibility and effectiveness of the model.
RETRACTED: Robot Path Planning Method Based on Indoor Spacetime Grid Model
Authors: Zhang Huangchuang , Zhuang Qingjun , Li Ge
Published: May 2022

In the context of digital twins, smart city construction and artificial intelligence technology are developing rapidly, and more and more mobile robots are performing tasks in complex and time-varying indoor environments, making, at present, the unification of modeling, dynamic expression, visualization of operation, and wide application between robots and indoor environments a pressing problem to be solved. This paper presents an in-depth study on this issue and summarizes three major types of methods: geometric modeling, topological modeling, and raster modeling, and points out the advantages and disadvantages of these three types of methods. Therefore, in view of the current pain points of robots and complex time-varying indoor environments, this paper proposes an indoor spacetime grid model based on the three-dimensional division framework of the Earth space and innovatively integrates time division on the basis of space division. On the basis of the model, a dynamic path planning algorithm for the robot in the complex time-varying indoor environment is designed, that is, the Spacetime-A* algorithm (STA* for short). Finally, the indoor spacetime grid modeling experiment is carried out with real data, which verifies the feasibility and correctness of the spacetime relationship calculation algorithm encoded by the indoor spacetime grid model. Then, experiments are carried out on the multi-group path planning algorithms of the robot under the spacetime grid, and the feasibility of the STA* algorithm under the indoor spacetime grid and the superiority of the spacetime grid are verified.
Using Remote Sensing to Estimate Understorey Biomass in Semi-Arid Woodlands of South-Eastern Australia
Authors: Riquelme Linda , Duncan David H. , Rumpff Libby , Vesk Peter Anton
Published: May 2022

Monitoring ground layer biomass, and therefore forage availability, is important for managing large, vertebrate herbivore populations for conservation. Remote sensing allows for frequent observations over broad spatial scales, capturing changes in biomass over the landscape and through time. In this study, we explored different satellite-derived vegetation indices (VIs) for their utility in estimating understorey biomass in semi-arid woodlands of south-eastern Australia. Relationships between VIs and understorey biomass data have not been established in these particular semi-arid communities. Managers want to use forage availability to inform cull targets for western grey kangaroos (Macropus fuliginosus), to minimise the risk that browsing poses to regeneration in threatened woodland communities when grass biomass is low. We attempted to develop relationships between VIs and understorey biomass data collected over seven seasons across open and wooded vegetation types. Generalised Linear Mixed Models (GLMMs) were used to describe relationships between understorey biomass and VIs. Total understorey biomass (live and dead, all growth forms) was best described using the Tasselled Cap (TC) greenness index. The combined TC brightness and Modified Soil Adjusted Vegetation Index (MSAVI) ranked best for live understorey biomass (all growth forms), and grass (live and dead) biomass was best described by a combination of TC brightness and greenness indices. Models performed best for grass biomass, explaining 70% of variation in external validation when predicting to the same sites in a new season. However, we found empirical relationships were not transferrable to data collected from new sites. Including other variables (soil moisture, tree cover, and dominant understorey growth form) improved model performance when predicting to new sites. Anticipating a drop in forage availability is critical for the management of grazing pressure for woodland regeneration, however, predicting understorey biomass through space and time is a challenge. Whilst remotely sensed VIs are promising as an easily-available source of vegetation information, additional landscape-scale data are required before they can be considered a cost-efficient method of understorey biomass estimation in this semi-arid landscape.
Non-Uniform Synthetic Aperture Radiometer Image Reconstruction Based on Deep Convolutional Neural Network
Authors: Xiao Chengwang , Wang Xi , Dou Haofeng , Li Hao , Lv Rongchuan , Wu Yuanchao , Song Guangnan , Wang Wenjin , Zhai Ren
Published: May 2022

When observing the Earth from space, the synthetic aperture radiometer antenna array is sometimes set as a non-uniform array. In non-uniform synthetic aperture radiometer image reconstruction, the existing brightness temperature image reconstruction methods include the grid method and array factor forming (AFF) method. However, when using traditional methods for imaging, errors are usually introduced or some prior information is required. In this article, we propose a new IASR imaging method with deep convolution neural network (CNN). The frequency domain information is extracted through multiple convolutional layers, global pooling layers, and fully connected layers to achieve non-uniform synthetic aperture radiometer imaging. Through extensive numerical experiments, we demonstrate the performance of the proposed imaging method. Compared to traditional imaging methods such as the grid method and AFF method, the proposed method has advantages in image quality, computational efficiency, and noise suppression.
A New Coupling Method for PM2.5 Concentration Estimation by the Satellite-Based Semiempirical Model and Numerical Model
Authors: Yuan Shuyun , Li Ying , Gao Jinhui , Bao Fangwen
Published: May 2022

Aerosol optical and chemical properties play a major role in the retrieval of PM2.5 concentrations based on aerosol optical depth (AOD) data from satellites in the conventional semiempirical model (SEM). However, limited observation information hinders the high-resolution estimation of PM2.5. Therefore, a new method for evaluating near-surface PM2.5 at high spatial resolution is developed by coupling the SEM and the chemical transport model (CTM)-based numerical (CSEN) model. The numerical model can provide large-scale information for aerosol properties with high spatial resolution at a large scale based on emissions and meteorology, though it can still be biased in simulating absolute PM2.5 concentrations. Therefore, the two crucial aerosol characteristic parameters, including the coefficient integrated humidity effect (γ′) and the comprehensive reference value of aerosol properties (K) in SEM, have been redefined using the WRF-Chem numerical model. Improved model performance was observed for these results compared with the original SEM results. The monthly averaged correlation coefficients (R) by CSEN were 0.92, 0.82, 0.84, and 0.83 in January, April, July, and October, respectively, whereas those of the SEM were 0.80, 0.77, 0.72, and 0.72, respectively. All the statistical metrics of the model validation showed significant improvements in all seasons. The reduced biases of estimated PM2.5 by CSEN indicated the effect of hygroscopic growth and aerosol properties affected by the meteorology on the relationship between AOD and estimated PM2.5 concentrations, especially in winter and summer. The better performance of the CSEN model provides insight for air quality monitoring at different scales, which supplies important information for air pollution control policies and health impact analysis.
Correcting GEDI Water Level Estimates for Inland Waterbodies Using Machine Learning
Authors: Fayad Ibrahim , Baghdadi Nicolas , Bailly Jean-Stéphane , Frappart Frédéric , Pantaleoni Reluy Núria
Published: May 2022

The Global Ecosystem Dynamics Investigation (GEDI) LiDAR on the International Space Station has acquired more than 35 billion shots globally in the period between April 2019 and August 2021. The acquired shots could offer a significant database for the measure and monitoring of inland water levels over the Earth’s surface. Nonetheless, previous and current studies have shown that the provided GEDI elevation estimates are significantly less accurate than any available radar or LiDAR altimeter. Indeed, our analysis of GEDI’s altimetric capabilities to retrieve water levels over the five North American Great Lakes presented estimates with a bias that ranged between 0.26 and 0.35 m and a root mean squared error (RMSE) ranging between 0.54 and 0.68 m. Therefore, our objective in this study is to post-process the original GEDI water level estimates from an error model taking instrumental, atmospheric, and lakes surface state factors as proxies, which affect the physical shape of the waveforms, hence introducing uncertainties on the elevation estimates. The first tested model, namely a random forest regressor (RFICW) with the instrumental, atmospheric, and water surface state factors as inputs, was validated temporally (trained on a given year and validated on another) and spatially (trained on a given lake and validated on the remaining four). The results showed a significant decrease in elevation estimation errors both temporally and spatially. The temporally validated models showed an RMSE on the corrected elevation estimates of 0.18 m. Concerning the spatially validated model, the results varied based on the lake data used for training. Indeed, the most accurate spatially validated model showed an RMSE of 0.17 m, while the least accurate model showed an RMSE of 0.26 m. Finally, given that an elevation correction model using all the factors (instrumental, atmospheric, and water surface state factors) presents a best-case scenario, as water surface state factors are only available over a selected number of lakes globally, three additional models based on random forest were tested. The first, RFI, uses only instrumental factors as correction factors, RFIC uses both instrumental and atmospheric factors, while the third, RFIW, uses instrumental and water surface state factors. The temporal validation of these models showed that the model using instrumental factors, while less accurate than the remaining two models, was capable of correcting the original GEDI elevation estimates by a factor of two across the five lakes. On the other hand, the RFIC model was the most accurate between the three, with a slight degradation in comparison to the full model. Indeed, the RFIC model showed an RMSE on the estimation of water levels of 0.21 m.
Performance Analysis of Ku/Ka Dual-Band SAR Altimeter from an Airborne Experiment over South China Sea
Authors: Liu Xiaonan , Kong Weiya , Sun Hanwei , Lu Yaobing
Published: May 2022

Satellite radar altimeters have been successfully used for sea surface height (SSH) measurement for decades, gaining great insight in oceanography, meteorology, marine geology, etc. To further improve the observation precision and spatial resolution, radar altimeters have evolved from real aperture to synthetic aperture, from the Ku-band to Ka-band. Future synthetic aperture radar (SAR) altimeter of the Ka-band is expected to achieve better performance than its predecessors. To verify the SAR altimeter data processing method and explore the system advantage of the Ka-band, a Ku/Ka dual-band SAR altimeter airborne experiment was carried out over South China Sea on 6 November 2021. Through dedicated hardware design, this campaign has acquired the Ku and Ka dual-band echo data simultaneously. The airborne data are processed to estimate the SSH retrieval precision after a series of procedures (including height compensation, range migration correction, multi-look processing, waveform re-tracking). To accustom to the airborne experiment design, a SAR echo model that fully considers both the attitude variation of the aircraft and the elliptical footprint of radar beam is established. The retrieved SSH data are compared with the public SSH data along the flight path at the experiment day, showing good consistence for both bands. By calculating the theoretical precision of waveform re-tracking and re-processing the dual-band airborne data into different bandwidths, it is demonstrated that the Ku/Ka precision ratio is possible to achieve 1.4 within the 27 km offshore area, which indicates that Ka-band has better performance.