bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface Modification of Cellulose from Oat Hull with Citric Acid Using Ultrasonication and Reactive Extrusion Assisted Processes
Authors: Gil Giraldo Gina Alejandra , Mantovan Janaina , Marim Beatriz M. , Kishima João Otávio F. , Mali Suzana
Published: April 2021

This study aimed to produce modified cellulose extracted from oat hulls by an esterification reaction with citric acid (CA) employing ultrasonication and reactive extrusion assisted processes. Modified samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (DRX), scanning electron microscopy (SEM), wettability, oil and water absorption capacities, water adsorption capacity, and thermal stability. From FTIR results it can be observed a new band for all modified samples at 1735 cm−1, confirming the esterification. The morphology and crystallinity pattern of fibers were not affected by esterification, and crystallinity indexes ranged from 43% (unmodified cellulose) to 44–49% in modified samples. Both groups of samples, obtained by ultrasonication and reactive extrusion, showed decreases in water absorption capacities (1.63–1.71 g/g) compared to unmodified cellulose (9.38 g/g). It was observed an increase in oil retention capacity from 1.80 g/g (unmodified cellulose) to 4.57–7.31 g/g after esterification, and also the modified samples presented higher affinity by a non-polar solvent in the wettability test. The new properties of modified cellulose expand its use in the industry and prove that ultrasonication and reactive extrusion can be used to obtain esterified cellulose, being eco-friendly, simple, and convenient processes with short reaction times.
The Prophet and the Poet: Richard Shaull and the Shaping of Rubem Alves’s Liberative Theopoetics
Authors: Barreto Raimundo C.
Published: April 2021

This article explores the intersection between history, mission, and theology in Latin America by shedding light on the encounter between North American missionary Richard Shaull and Brazilian theologian and poet Rubem Alves. It examines Shaull’s impact on Alves as Alves became, first, one of the founders of Latin American liberation theology and, later, one of its challengers as he moved away from normative theological language towards theopoetics. In this article, I underscore particular snapshots of Alves’ vast work, noting that the images of the poet and the prophet that permeate much of it are not mutually exclusive. I argue that Rubem Alves’ provocative work remains an important resource for a theory of action that takes subjectivity and beauty seriously. Throughout this article, Shaull and Alves are presented as different but complementary thinkers, representative of Alves’ prophetic and poetic types. It is argued that a closer look at the similarities and complementarities in the works of this duo may provide us with new insights through which Rubem Alves’ poetic voice and Richard Shaull’s prophetic persistence can come together as resources for the reimagination of our hopes for a more beautiful and just world.
Applications of Unmanned Aerial Systems (UASs) in Hydrology: A Review
Authors: Vélez-Nicolás Mercedes , García-López Santiago , Barbero Luis , Ruiz-Ortiz Verónica , Sánchez-Bellón Ángel
Published: April 2021

In less than two decades, UASs (unmanned aerial systems) have revolutionized the field of hydrology, bridging the gap between traditional satellite observations and ground-based measurements and allowing the limitations of manned aircraft to be overcome. With unparalleled spatial and temporal resolutions and product-tailoring possibilities, UAS are contributing to the acquisition of large volumes of data on water bodies, submerged parameters and their interactions in different hydrological contexts and in inaccessible or hazardous locations. This paper provides a comprehensive review of 122 works on the applications of UASs in surface water and groundwater research with a purpose-oriented approach. Concretely, the review addresses: (i) the current applications of UAS in surface and groundwater studies, (ii) the type of platforms and sensors mainly used in these tasks, (iii) types of products generated from UAS-borne data, (iv) the associated advantages and limitations, and (v) knowledge gaps and future prospects of UASs application in hydrology. The first aim of this review is to serve as a reference or introductory document for all researchers and water managers who are interested in embracing this novel technology. The second aim is to unify in a single document all the possibilities, potential approaches and results obtained by different authors through the implementation of UASs.
High-Resolution Monitoring of Tidal Systems Using UAV: A Case Study on Poplar Island, MD (USA)
Authors: Taddia Yuri , Pellegrinelli Alberto , Corbau Corinne , Franchi Giulia , Staver Lorie W. , Stevenson John Court , Nardin William
Published: April 2021

Tidal processes regulating sediment accretion rates and vegetated platform erosion in tidal systems strongly affect salt marsh evolution. A balance between erosion and deposition in a restored salt marsh is crucial for analyzing restoration strategies to be adopted within a natural context. Marsh morphology is also coupled with tidal mudflats and channel networks and this makes micro-tidal systems crucial for a detailed assessment of restoration interventions. Here, we present a methodological approach for monitoring channel morphodynamics and vegetation variations over a time frame of six years in a low tidal energy salt marsh of the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island (Maryland, USA). The project is a restoration site where sediment dredged from the shipping channels in the upper Chesapeake Bay is used to restore a tidal marsh habitat in mid-Chesapeake Bay. Aerial surveys with an Unmanned Aerial Vehicle (UAV) have been performed for the high-resolution mapping of a small tidal system. Flight missions were planned to obtain a Ground Sample Distance (GSD) of 2 cm. Structure-from-Motion (SfM) and Multi-View-Stereo (MVS) algorithms have been used to reconstruct the 3D geometry of the site. The mapping of channel morphology and an elevation assessment on the mudflat were performed using orthomosaics, Digital Terrain Models (DTMs) and GNSS survey. The results highlight that the workflow adopted in this pilot work is suitable to assess the geomorphological evolution over time in a micro-tidal system. However, issues were encountered for salt marsh due to the presence of dense vegetation. The UAV-based photogrammetry approach with GNSS RTK ground surveys can hence be replicated in similar sites all over the world to evaluate restoration interventions and to develop new strategies for a better management of existing shorelines.
Spatiotemporal Variation in Ecosystem Services and Their Drivers among Different Landscape Heterogeneity Units and Terrain Gradients in the Southern Hill and Mountain Belt, China
Authors: Wang Liang-Jie , Ma Shuai , Jiang Jiang , Zhao Yu-Guo , Zhang Jin-Chi
Published: April 2021

Understanding the spatiotemporal heterogeneity of ecosystem services (ESs) and their drivers in mountainous areas is important for sustainable ecosystem management. However, the effective construction of landscape heterogeneous units (LHUs) to reflect the spatial characteristics of ESs remains to be studied. The southern hill and mountain belt (SHMB) is a typical mountainous region in China, with undulating terrain and obvious spatial heterogeneity of ESs, and was selected as the study area. In this study, we used the fuzzy k-means (FKM) algorithm to establish LHUs. Three major ESs (water yield, net primary productivity (NPP), and soil conservation) in 2000 and 2015 were quantified using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model and Carnegie Ames-Stanford approach (CASA) model. Then, we explored the spatial variation in ESs along terrain gradients and LHUs. Correlation analysis was used to analyze the driving factors of ESs in each terrain region and LHU. The results showed that altitude and terrain niche increased along LHUs. Water yield and soil conservation increased from 696.86 mm and 3920.19 t/km2 to 1061.12 mm and 5117.90 t/km2, respectively, while NPP decreased from 666.95 gC/m2 to 648.86 gC/m2. The ESs in different LHUs differed greatly. ESs increased first and then decreased along LHUs in 2000. In 2015, water yield decreased along LHUs, while NPP and soil conservation showed a fluctuating trend. Water yield was mainly affected by precipitation, temperature and NDVI were the main drivers of NPP, and soil conservation was greatly affected by precipitation and slope. The driving factors of the same ES were different in different terrain areas and LHUs. The variation and driving factors of ESs in LHUs were similar to some terrain gradients. To some extent, LHUs can represent multiple terrain features. This study can provide important support for mountain ecosystem zoning management and decision-making.
Strategies for the Development of Spectral Models for Soil Organic Matter Estimation
Authors: Cezar Everson , Nanni Marcos Rafael , Crusiol Luís Guilherme Teixeira , Sun Liang , Chicati Mônica Sacioto , Furlanetto Renato Herrig , Rodrigues Marlon , Sibaldelli Rubson Natal Ribeiro , Silva Guilherme Fernando Capristo , Oliveira Karym Mayara de , Demattê José A. M.
Published: April 2021

Visible (V), Near Infrared (NIR) and Short Waves Infrared (SWIR) spectroscopy has been indicated as a promising tool in soil studies, especially in the last decade. However, in order to apply this method, it is necessary to develop prediction models with the capacity to capture the intrinsic differences between agricultural areas and incorporate them in the modeling process. High quality estimates are generally obtained when these models are applied to soil samples displaying characteristics similar to the samples used in their construction. However, low quality predictions are noted when applied to samples from new areas presenting different characteristics. One way to solve this problem is by recalibrating the models using selected samples from the area of interest. Based on this premise, the aim of this study was to use the spiking technique and spiking associated with hybridization to expand prediction models and estimate organic matter content in a target area undergoing different uses and management. A total of 425 soil samples were used for the generation of the state model, as well as 200 samples from a target area to select the subsets (10 samples) used for model recalibration. The spectral readings of the samples were obtained in the laboratory using the ASD FieldSpec 3 Jr. Sensor from 350 to 2500 nm. The spectral curves of the samples were then associated to the soil attributes by means of a partial least squares regression (PLSR). The state model obtained better results when recalibrated with samples selected through a cluster analysis. The use of hybrid spectral curves did not generate significant improvements, presenting estimates, in most cases, lower than the state model applied without recalibration. The use of the isolated spiking technique was more effective in comparison with the spiked and hybridized state models, reaching r2, square root of mean prediction error (RMSEP) and ratio of performance to deviation (RPD) values of 0.43, 4.4 g dm−3, and 1.36, respectively.
WHISPER: A Location Privacy-Preserving Scheme Using Transmission Range Changing for Internet of Vehicles
Authors: Babaghayou Messaoud , Labraoui Nabila , Abba Ari Ado Adamou , Ferrag Mohamed Amine , Maglaras Leandros , Janicke Helge
Published: April 2021

Internet of Vehicles (IoV) has the potential to enhance road-safety with environment sensing features provided by embedded devices and sensors. This benignant feature also raises privacy issues as vehicles announce their fine-grained whereabouts mainly for safety requirements, adversaries can leverage this to track and identify users. Various privacy-preserving schemes have been designed and evaluated, for example, mix-zone, encryption, group forming, and silent-period-based techniques. However, they all suffer inherent limitations. In this paper, we review these limitations and propose WHISPER, a safety-aware location privacy-preserving scheme that adjusts the transmission range of vehicles in order to prevent continuous location monitoring. We detail the set of protocols used by WHISPER, then we compare it against other privacy-preserving schemes. The results show that WHISPER outperformed the other schemes by providing better location privacy levels while still fulfilling road-safety requirements.
Spatial-Variant SAR Range Cell Migration Correction Using Subaperture Strategy
Authors: Hu Liping , Wang Guanyong , Hou Lin
Published: April 2021

The coupling between range and azimuth dimensions is the main obstacle for highly squinted synthetic aperture radar (SAR) data focusing. Range walk correction (RWC) processing is effective to remove the linear coupling term, but the residual high order range cell migration (RCM) parts are spatial-variant in both range and azimuth dimensions. In this paper, we propose a precise spatial-variant range cell migration correction (RCMC) method with subaperture processing. The method contains two stages. Firstly, the main component of range-variant RCM is corrected in the coarse RCMC stage. Secondly, data are derived into azimuth subapertures (SAs), an SA-image-domain RCMC is developed by interp correction, where the SA image is obtained using a modified spectrum analysis (SPECAN) algorithm by establishing the relationship between Doppler frequency and residual spatial-variant RCM. In the proposed algorithm, precise compensation of space-variant RCM is implemented by SA processing, which is designed for a better practicality in real-time processing system. Simulated and real measured data experiments are designed to validate the effectiveness of the proposed approach for highly squinted SAR imaging.
An Examination System to Detect Deep Vein Thrombosis of a Lower Limb Using Light Reflection Rheography
Authors: Liu Shing-Hong , Wang Jia-Jung , Chen Wenxi , Pan Kuo-Li , Su Chun-Hung
Published: April 2021

Deep vein thrombosis (DVT) of lower limbs can easily arise from prolonged sitting or standing. Elders and pregnant women are most likely to have this disease. When the embolus of DVT comes to pass the lung, it will become a life-threatening disease. Thus, for DVT disease, early detection and the early treatment are needed. The goal of this study was to develop an examination system to be used at non-medical places to detect the DVT of lower limbs with light reflection rheography (LRR). Consisting of a wearable device and a mobile application (APP), the system is operated in a wireless manner to control the actions of sensors and display and store the LRR signals on the APP. Then, the recorded LRR signals are processed to find the parameters of DVT examination. Twenty subjects were recruited to perform experiments. The veins of lower limbs were occluded by pressuring the cuff up to 100 mmHg and 150 mmHg to simulate the slight and serious DVT scenarios, respectively. Six characteristic parameters were defined to classify whether there was positive or negative DVT using the receiver operating characteristic curves, including the slopes of emptying and refilling curves in the LRR signal, and the changes of venous pump volume. Under the slight DVT scenario (0 mmHg vs. 100 mmHg), the first three parameters, m10, m40, and m50, had accuracies of 72%, 69%, and 69%, respectively. Under the serious DVT scenario (0 mmHg vs. 150 mmHg), m10, m40, and m50 achieved accuracies of 73%, 76%, and 73%, respectively. The experimental results show that this proposed examination system may be practical as an auxiliary tool to screen DVT in homecare settings.
A BCI Based Alerting System for Attention Recovery of UAV Operators
Authors: Park Jonghyuk , Park Jonghun , Shin Dongmin , Choi Yerim
Published: April 2021

As unmanned aerial vehicles have become popular, the number of accidents caused by an operator’s inattention have increased. To prevent such accidents, the operator should maintain an attention status. However, limited research has been conducted on the brain-computer interface (BCI)-based system with an alerting module for the operator’s attention recovery of unmanned aerial vehicles. Therefore, we introduce a detection and alerting system that prevents an unmanned aerial vehicle operator from falling into inattention status by using the operator’s electroencephalogram signal. The proposed system consists of the following three components: a signal processing module, which collects and preprocesses an electroencephalogram signal of an operator, an inattention detection module, which determines whether an inattention status occurred based on the preprocessed signal, and, lastly, an alert providing module that presents stimulus to an operator when inattention is detected. As a result of evaluating the performance with a real-world dataset, it was shown that the proposed system successfully contributed to the recovery of operator attention in the evaluating dataset, although statistical significance could not be established due to the small number of subjects.
A Study on Real Time IGBT Junction Temperature Estimation Using the NTC and Calculation of Power Losses in the Automotive Inverter System
Authors: Lim Heesun , Hwang Jaeyeob , Kwon Soonho , Baek Hyunjun , Uhm Juneik , Lee GeunHo
Published: April 2021

This paper proposes a junction temperature estimation algorithm for the insulated gate bipolar transistor (IGBT) based on a power loss calculation and a thermal impedance model for inverter systems. The Simulink model was designed to calculate the power losses of power semiconductor devices and to estimate the junction temperature with a simplified thermal impedance model. This model can estimate the junction temperature up to the transient state, including the steady state. The parameters used to calculate the power losses, the thermal resistance, and the thermal capacitance were optimized for a given inverter to be tested for improving the accuracy. The simulation results and experimental measurement data were compared to verify the proposed junction temperature estimation algorithm. Finally, the algorithm was installed on the inverter controller, and the performance was verified by comparing the real time estimation result with the measured temperature.
Potential of Dual and Multi Energy XRT and CT Analyses on Iron Formations
Authors: Bauer Christine , Wagner Rebecca , Orberger Beate , Firsching Markus , Ennen Alexander , Garcia Pina Carlos , Wagner Christiane , Honarmand Maryam , Nabatian Ghasem , Monsef Iman
Published: April 2021

Dual and multi energy X-ray transmission imaging (DE-/ME-XRT) are powerful tools to acquire quantitative material characteristics of diverse samples without destruction. As those X-ray imaging techniques are based on the projection onto the imaging plane, only two-dimensional data can be obtained. To acquire three-dimensional information and a complete examination on topology and spatial trends of materials, computed tomography (CT) can be used. In combination, these methods may offer a robust non-destructive testing technique for research and industrial applications. For example, the iron ore mining and processing industry requires the ratio of economic iron minerals to siliceous waste material for resource and reserve estimations, and for efficient sorting prior to beneficiation, to avoid equipment destruction due to highly abrasive quartz. While XRT provides information concerning the thickness, areal density and mass fraction of iron and the respective background material, CT may deliver size, distribution and orientation of internal structures. Our study shows that the data provided by XRT and CT is reliable and, together with data processing, can be successfully applied for distinguishing iron oxide rich parts from waste. Furthermore, heavy element bearing minerals such as baryte, uraninite, galena and monazite can be detected.
Smartwatch User Authentication by Sensing Tapping Rhythms and Using One-Class DBSCAN
Authors: Zhang Hanqi , Xiao Xi , Ni Shiguang , Dou Changsheng , Zhou Wei , Xia Shutao
Published: April 2021

As important sensors in smart sensing systems, smartwatches are becoming more and more popular. Authentication can help protect the security and privacy of users. In addition to the classic authentication methods, behavioral factors can be used as robust measures for this purpose. This study proposes a lightweight authentication method for smartwatches based on edge computing, which identifies users by their tapping rhythms. Based on the DBSCAN clustering algorithm, a new classification method called One-Class DBSCAN is presented. It first seeks core objects and then leverages them to perform user authentication. We conducted extensive experiments on 6110 real data samples collected from more than 600 users. The results show that our method achieved the lowest Equal Error Rate (EER) of only 0.92%, which was lower than those of other state-of-the-art methods. In addition, a statistical method for detecting the security level of a tapping rhythm is proposed. It can prevent users from setting a simple tapping rhythm password, and thus improve the security of smartwatches.
Blockchain-Based Access Control Scheme for Secure Shared Personal Health Records over Decentralised Storage
Authors: Hussien Hassan , Yasin Sharifah , Udzir Nur , Ninggal Mohd
Published: April 2021

Blockchain technology provides a tremendous opportunity to transform current personal health record (PHR) systems into a decentralised network infrastructure. However, such technology possesses some drawbacks, such as issues in privacy and storage capacity. Given its transparency and decentralised features, medical data are visible to everyone on the network and are inappropriate for certain medical applications. By contrast, storing vast medical data, such as patient medical history, laboratory tests, X-rays, and MRIs, significantly affect the repository storage of blockchain. This study bridges the gap between PHRs and blockchain technology by offloading the vast medical data into the InterPlanetary File System (IPFS) storage and establishing an enforced cryptographic authorisation and access control scheme for outsourced encrypted medical data. The access control scheme is constructed on the basis of the new lightweight cryptographic concept named smart contract-based attribute-based searchable encryption (SC-ABSE). This newly cryptographic primitive is developed by extending ciphertext-policy attribute-based encryption (CP-ABE) and searchable symmetric encryption (SSE) and by leveraging the technology of smart contracts to achieve the following: (1) efficient and secure fine-grained access control of outsourced encrypted data, (2) confidentiality of data by eliminating trusted private key generators, and (3) multikeyword searchable mechanism. Based on decisional bilinear Diffie–Hellman hardness assumptions (DBDH) and discrete logarithm (DL) problems, the rigorous security indistinguishability analysis indicates that SC-ABSE is secure against the chosen-keyword attack (CKA) and keyword secrecy (KS) in the standard model. In addition, user collusion attacks are prevented, and the tamper-proof resistance of data is ensured. Furthermore, security validation is verified by simulating a formal verification scenario using Automated Validation of Internet Security Protocols and Applications (AVISPA), thereby unveiling that SC-ABSE is resistant to man-in-the-middle (MIM) and replay attacks. The experimental analysis utilised real-world datasets to demonstrate the efficiency and utility of SC-ABSE in terms of computation overhead, storage cost and communication overhead. The proposed scheme is also designed and developed to evaluate throughput and latency transactions using a standard benchmark tool known as Caliper. Lastly, simulation results show that SC-ABSE has high throughput and low latency, with an ultimate increase in network life compared with traditional healthcare systems.
Elastic Wave Monitoring of Cementitious Mixtures Including Internal Curing Mechanisms
Authors: Lefever Gerlinde , Snoeck Didier , De Belie Nele , Van Hemelrijck Danny , Aggelis Dimitrios G.
Published: April 2021

The mitigation of autogenous shrinkage in cementitious materials by internal curing has been widely studied. By the inclusion of water reservoirs, in form of saturated lightweight aggregates or superabsorbent polymers, additional water is provided to the hydrating matrix. The onset of water release is of high importance and determines the efficiency of the internal curing mechanism. However, the monitoring of it poses problems as it is a process that takes place in the microstructure. Using acoustic emission (AE) sensors, the internal curing process is monitored, revealing its initiation and intensity, as well as the duration. In addition, AE is able to capture the water evaporation from saturated specimens. By ultrasonic testing, differences in the hydration kinetics are observed imposed by the different methods of internal curing. The results presented in this paper show the sensitivity of combined AE and ultrasound experiments to various fundamental mechanisms taking place inside cementitious materials and demonstrate the ability of acoustic emission to evaluate internal curing in a non-destructive and easily implementable way.
Characterization of Shear Horizontal Waves Using a 1D Laser Doppler Vibrometer
Authors: Elhady Alaa , Abdel-Rahman Eihab M.
Published: April 2021

We developed a new technique for the detection of shear horizontal surface acoustic waves (SH-SAW) using a one-dimensional laser-based Doppler vibrometer. It measures the out-of-plane surface deformation at the fingertip of an interdigitated transducer (the boundary of the wave aperture) and uses it to estimate the instantaneous in-plane displacement field given the substrate Poisson ratio. It can also estimate the degree of surface confinement (wave decay rate). The proposed approach was first verified using finite element analysis (FEA) and demonstrated experimentally using a Bleustein–Gulyaev resonator.
An Improved Localization Method for the Transition between Autonomous Underwater Vehicle Homing and Docking
Authors: Lin Ri , Zhang Feng , Li Dejun , Lin Mingwei , Zhou Gengli , Yang Canjun
Published: April 2021

Docking technology for autonomous underwater vehicles (AUVs) involves energy supply, data exchange and navigation, and plays an important role to extend the endurance of the AUVs. The navigation method used in the transition between AUV homing and docking influences subsequent tasks. How to improve the accuracy of the navigation in this stage is important. However, when using ultra-short baseline (USBL), outliers and slow localization updating rates could possibly cause localization errors. Optical navigation methods using underwater lights and cameras are easily affected by the ambient light. All these may reduce the rate of successful docking. In this paper, research on an improved localization method based on multi-sensor information fusion is carried out. To improve the localization performance of AUVs under motion mutation and light variation conditions, an improved underwater simultaneous localization and mapping algorithm based on ORB features (IU-ORBSALM) is proposed. A nonlinear optimization method is proposed to optimize the scale of monocular visual odometry in IU-ORBSLAM and the AUV pose. Localization tests and five docking missions are executed in a swimming pool. The localization results indicate that the localization accuracy and update rate are both improved. The 100% successful docking rate achieved verifies the feasibility of the proposed localization method.
Mobility-Aware Privacy-Preserving Mobile Crowdsourcing
Authors: Qiu Guoying , Shen Yulong , Cheng Ke , Liu Lingtong , Zeng Shuiguang
Published: April 2021

The increasing popularity of smartphones and location-based service (LBS) has brought us a new experience of mobile crowdsourcing marked by the characteristics of network-interconnection and information-sharing. However, these mobile crowdsourcing applications suffer from various inferential attacks based on mobile behavioral factors, such as location semantic, spatiotemporal correlation, etc. Unfortunately, most of the existing techniques protect the participant’s location-privacy according to actual trajectories. Once the protection fails, data leakage will directly threaten the participant’s location-related private information. It open the issue of participating in mobile crowdsourcing service without actual locations. In this paper, we propose a mobility-aware trajectory-prediction solution, TMarkov, for achieving privacy-preserving mobile crowdsourcing. Specifically, we introduce a time-partitioning concept into the Markov model to overcome its traditional limitations. A new transfer model is constructed to record the mobile user’s time-varying behavioral patterns. Then, an unbiased estimation is conducted according to Gibbs Sampling method, because of the data incompleteness. Finally, we have the TMarkov model which characterizes the participant’s dynamic mobile behaviors. With TMarkov in place, a mobility-aware spatiotemporal trajectory is predicted for the mobile user to participate in the crowdsourcing application. Extensive experiments with real-world dataset demonstrate that TMarkov well balances the trade-off between privacy preservation and data usability.
Development and Evaluation of a Low-Drift Inertial Sensor-Based System for Analysis of Alpine Skiing Performance
Authors: Ruiz-García Isidoro , Navarro-Marchal Ismael , Ocaña-Wilhelmi Javier , Palma Alberto J. , Gómez-López Pablo J. , Carvajal Miguel A.
Published: April 2021

In skiing it is important to know how the skier accelerates and inclines the skis during the turn to avoid injuries and improve technique. The purpose of this pilot study with three participants was to develop and evaluate a compact, wireless, and low-cost system for detecting the inclination and acceleration of skis in the field based on inertial measurement units (IMU). To that end, a commercial IMU board was placed on each ski behind the skier boot. With the use of an attitude and heading reference system algorithm included in the sensor board, the orientation and attitude data of the skis were obtained (roll, pitch, and yaw) by IMU sensor data fusion. Results demonstrate that the proposed IMU-based system can provide reliable low-drifted data up to 11 min of continuous usage in the worst case. Inertial angle data from the IMU-based system were compared with the data collected by a video-based 3D-kinematic reference system to evaluate its operation in terms of data correlation and system performance. Correlation coefficients between 0.889 (roll) and 0.991 (yaw) were obtained. Mean biases from −1.13° (roll) to 0.44° (yaw) and 95% limits of agreements from 2.87° (yaw) to 6.27° (roll) were calculated for the 1-min trials. Although low mean biases were achieved, some limitations arose in the system precision for pitch and roll estimations that could be due to the low sampling rate allowed by the sensor data fusion algorithm and the initial zeroing of the gyroscope.
Autonomous Mission of Multi-UAV for Optimal Area Coverage
Authors: Hong Youkyung , Jung Sunggoo , Kim Suseong , Cha Jihun
Published: April 2021

This study proposes an entire hardware and software architecture from operator input to motor command for the autonomous area coverage mission using multiple unmanned aerial vehicles. Despite the rapid growth of commercial drone services, there are many limitations on operations, such as a low decision-making autonomy and the need for experienced operators to intervene in the whole process. For performing the area coverage mission more efficiently and autonomously, this study newly designs an optimization problem that allocates waypoints created to cover that area to unmanned aerial vehicles. With an optimized list of waypoints, unmanned aerial vehicles can fill the given areas with their footprints in a minimal amount of time and do not overlap each other during the mission. In addition, this study performs both various simulations for quantitative analysis and an outdoor experiment through real hardware implementation in order to verify the performance sufficiently. The methodologies developed in this study could be applied to endless applications using unmanned aerial vehicles equipped with mission-specific sensors.
A Comprehensive Open-Source Simulation Framework for LiFi Communication
Authors: Ullah Shakir , Rehman Saeed Ur , Chong Peter Han Joo
Published: April 2021

Light Fidelity (LiFi) is a new candidate for wireless networking that utilizes the visible light spectrum and exploits the existing lighting infrastructure in the form of light-emitting diodes (LEDs). It provides point-to-point and point-to-multipoint communication on a bidirectional channel at very high data rates. However, the LiFi has small coverage, and its optical gain is closely related to the receiver’s directionality vis-à-vis the transmitter, therefore it can experience frequent service outages. To provide reliable coverage, the LiFi is integrated with other networking technologies such as wireless fidelity (WiFi) thus forming a hybrid system. The hybrid LiFi/WiFi system faces many challenges including but not limited to seamless integration with the WiFi, support for mobility, handover management, resource sharing, and load balancing. The existing literature has addressed one or the other aspect of the issues facing LiFi systems. There are limited free source tools available to holistically address these challenges in a scalable manner. To this end, we have developed an open-source simulation framework based on the network simulator 3 (ns-3), which realizes critical aspects of the LiFi wireless network. Our developed ns-3 LiFi framework provides a fully functional AP equipped with the physical layer and medium access control (MAC), a mobility model for the user device, and integration between LiFi and WiFi with a handover facility. Simulation results are produced to demonstrate the mobility and handover capabilities, and the performance gains from the LiFi-WiFi hybrid system in terms of packet delay, throughput, packet drop ratio (PDR), and fairness between users. The source code of the framework is made available for the use of the research community.
Identifying and Zoning Key Areas of Ecological Restoration for Territory in Resource-Based Cities: A Case Study of Huangshi City, China
Authors: Zhang Can , Fang Shiming
Published: April 2021

Resource-based cities are cities that depend on the exploitation and primary processing of natural resources, such as minerals, metals, and oil, and whose rise and development are highly dependent on resources. Due to over exploitation, many problems related to ecosystem degradation have been caused. Ecological restoration of land space is urgent. One of the difficulties in carrying out ecological restoration of territorial space lies in the identification of key areas for ecological restoration and diagnosis of regional ecological problems. In this study, we applied the spatial assessment of ecological sensitivity and the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model to quantitatively analyze the overall ecosystem in Huangshi city so as to delimit the ecological restoration division of Huangshi City. The results showed that: (1) The overall distribution rule is that vegetation, such as that in mountains and forests, is dense, the sensitivity around water and wetlands is high, and the distribution of mines in Huangshi is high. (2) For the period 1980–2018, the habitat quality index of Huangshi was good, with a slight decreasing trend. The simulated habitat quality distribution was consistent with the region-dominated land cover type. (3) Huangshi formed a spatial pattern with natural protected areas as the priority protection areas, mining areas as the key restoration areas, and natural protected areas and mining areas as the general restoration areas. (4) During the period of 1980–2018, the water management of Huangshi generally improved, which indicates that the water pollution control in Huangshi had a positive effect. The results of this study can provide some reference for the green transformation development and ecological restoration of resource-based cities.
A Personality-Driven Recommender System for Cross-Domain Learning Based on Holland Code Assessments
Authors: Su Ja-Hwung , Liao Yi-Wen , Xu Jia-Zhen , Zhao Yu-Wei
Published: April 2021

Over the past few decades, AI has been widely used in the field of education. However, very little attention has been paid to the use of AI for enhancing the quality of cross-domain learning. College/university students are often interested in different domains of knowledge but may be unaware of how to choose relevant cross-domain courses. Therefore, this paper presents a personality-driven recommender system that suggests cross-domain courses and related jobs by computing personality similarities and probable course grades. In this study, 710 students from 12 departments in a Taiwanese university conducted Holland code assessments. Based on the assessments, a comprehensive empirical study, including objective and subjective evaluations, was performed. The results reveal that (1) the recommender system shows very promising performances in predicting course grades (objective evaluations), (2) most of the student testers had encountered difficulties in selecting cross-domain courses and needed the further support of a recommender system, and (3) most of the student testers positively rated the proposed system (subjective evaluations). In summary, Holland code assessments are useful for connecting personalities, interests and learning styles, and the proposed system provides helpful information that supports good decision-making when choosing cross-domain courses.
Optimizing Water Use Structures in Resource-Based Water-Deficient Regions Using Water Resources Input–Output Analysis: A Case Study in Hebei Province, China
Authors: Wei Yang , Sun Boyang
Published: April 2021

Hebei is a representative province facing the scarcity of water resource in China. China is promoting the coordinated development of Beijing, Tianjin, and Hebei, as well as the establishment of Xiong’an New Area. Hebei Province therefore has to bear the population pressure brought by the construction of Xiong’an New Area, while also absorbing the transfer of industries from Beijing and Tianjin. Therefore, its water supply tensions will be further exacerbated. This study constructed an input–output (IO) table utilizing the input and output data of Hebei in 2015 and analyzed the industrial structure and the characteristics of water usage in relevant industries. The research results show that the agricultural sector in Hebei Province consumes the highest water consumption per 10,000 yuan in output value, while the service and transportation industries are the lowest. And a large amount of water used in the agricultural sector is transferred to the manufacturing sector and construction sector in the form of virtual water. The main way to solve the contradiction between water supply and demand in the typical water-deficient areas represented by Hebei Province is to improve water resource utilization efficiency in the short term, and to change the regional water use structure through industrial structure adjustment in the long term.
Styles of Coping with Stress as a Factor Influencing Professional Burnout among Professional Officers of the Polish Army in the Context of Their Age
Authors: Bartkowiak Grażyna , Krugiełka Agnieszka , Kostrzewa-Demczuk Paulina , Dachowski Ryszard , Gałek Katarzyna
Published: April 2021

The subject of this article is the issue of coping with stress in the context of the level of professional burnout among professional soldiers at the officer rank and the identification of the relationship between occupational burnout and the preferences of the style of coping with stress and the age of the respondents. The study aims to answer the following questions: how does occupational burnout (its individual dimensions according to the concept underlying the construction of a research tool) depend on the style of coping with stress, and whether and how the level of occupational burnout changes depending on the age of soldiers? The study consists of two parts: a theoretical one, in which the issues are presented in relation to the literature on the subject, and an empirical section, presenting the results of research in which 200 soldiers of the Polish Army with the officer rank participated. The research was carried out using questionnaires that met the requirements of psychometric correctness (Coping Inventory for Stressful Situations—CISS and Link Burnout Questionnaire—LBQ). As a result of the research, it turned out that the level of occupational burnout depends on the choice of the style of coping with stress (a higher level of burnout is favored by the preference for an emotional coping strategy), while the style of coping with stress and the level of occupational burnout among professional soldiers with the rank of officer changes with age. The presented research, mainly due to the specifics of the research group, was not undertaken and described in the literature on the subject.
Caring for Things Helps Humans Grow: Effects of Courteous Interaction with Things on Pro-Environmental Behavior
Authors: Kamide Hiroko , Arai Tatsuo
Published: April 2021

The purpose of this study was to clarify the influence of courteous interaction with familiar objects on pro-environmental behavior and well-being. We explored the process of interaction with everyday objects, such as pens and glasses in a preliminary study (N = 64), and to reveal two aspects that define these interactions, namely active care for objects and awareness of learning from the interaction (N = 687; Study 1). The more people cared for and learned through their interactions with a particular object, the more they perceived a connectedness to it (N = 195; Study 2). Furthermore, caring for and learning with familiar objects promoted various environmentally conscious behaviors and contributed to individual well-being (Study 3; N = 600). In this way, we discussed the relationship between interaction with everyday objects, the aspects of these interactions, and the influence of these interactions on an individual’s perspective toward the wider environment.
Compulsive Buying in Adolescents. The Impact of Gender and Alcohol and Cannabis Use
Authors: Pérez de Albéniz-Garrote Gloria , Medina-Gómez Maria Begoña , Buedo-Guirado Cristina
Published: April 2021

The purpose of this study to analyse whether compulsive buying in teenagers is related to gender and alcohol and cannabis use in a sample of 573 students aged 14–17 from secondary education schools in Burgos (Spain) (M = 15.65; SD = 1.04). Random cluster sampling was performed to select the sample. The Compulsive Buying Questionnaire was used together with two extra promts: ‘Indicate how much alcohol you consume’ and ‘Indicate how much cannabis you take’. Descriptive statistics were used in data analysis, while MANOVA was used to study gender differences in alcohol and cannabis use, compulsive buying and their interaction. The results show higher scores for female compulsive buyers than for men, higher scores for alcohol and cannabis users’ compulsive buying than for non-users, respectively, and higher scores for female users than for male users. A certain interaction was also observed between alcohol and cannabis use. A higher alcohol consumption entailed a higher score in compulsive buying, with cannabis users who did not consume alcohol obtaining the highest scores. Thus, prevention programmes should consider teenagers’ gender and the risk of taking toxic substances.
Environmental Sustainability Analysis of Case Studies of Agriculture Residue Exploitation
Authors: Amato Alessia , Mastrovito Marianna , Becci Alessandro , Beolchini Francesca
Published: April 2021

The agriculture sector produces significant amounts of organic residues and the choice of the management strategy of these flows affects the environmental sustainability of the sector. The scientific literature is rich with innovative processes for the production of bio-based products (BBP) from agriculture residues, aimed at the implementation of circular economy principles. Based on literature data, the present paper performed a life cycle assessment and assessed the environmental sustainability of five processes for the exploitation of rice and wheat straw, tomato pomace, and orange peel. The analysis identified as significant issues the high energy demand and the use of high impact organic solvent. The comparison of BBP with conventional products showed higher environmental loads for the innovative processes that used organic residues (except for rice straw case). The obtained results do not want to discourage the circular strategy in the agriculture sector, but rather to draw the attention of all stakeholders to the environmental sustainability aspects, focusing on the necessity to decrease the electricity demand and identify ecological agents to use in BBP manufacturing, in agreement with the most recent European policies.
A Comparison between Second-Order Post-Newtonian Hamiltonian and Coherent Post-Newtonian Lagrangian in Spinning Compact Binaries
Authors: Cheng Xu-Hui , Huang Guo-Qing
Published: April 2021

In relativistic celestial mechanics, post-Newtonian (PN) Lagrangian and PN Hamiltonian formulations are not equivalent to the same PN order as our previous work in PRD (2015). Usually, an approximate Lagrangian is used to discuss the difference between a PN Hamiltonian and a PN Lagrangian. In this paper, we investigate the dynamics of compact binary systems for Hamiltonians and Lagrangians, including Newtonian, post-Newtonian (1PN and 2PN), and spin–orbit coupling and spin–spin coupling parts. Additionally, coherent equations of motion for 2PN Lagrangian are adopted here to make the comparison with Hamiltonian approaches and approximate Lagrangian approaches at the same condition and same PN order. The completely opposite nature of the dynamics shows that using an approximate PN Lagrangian is not convincing. Hence, using the coherent PN Lagrangian is necessary for obtaining an exact result in the research of dynamics of compact binary at certain PN order. Meanwhile, numerical investigations from the spinning compact binaries show that the 2PN term plays an important role in causing chaos in the PN Hamiltonian system.
Sasaki–Ricci Flow and Deformations of Contact Action–Angle Coordinates on Spaces T1,1 and Yp,q
Authors: Visinescu Mihai
Published: April 2021

In this paper, we are concerned with completely integrable Hamiltonian systems and generalized action–angle coordinates in the setting of contact geometry. We investigate the deformations of the Sasaki–Einstein structures, keeping the Reeb vector field fixed, but changing the contact form. We examine the modifications of the action–angle coordinates by the Sasaki–Ricci flow. We then pass to the particular cases of the contact structures of the five-dimensional Sasaki–Einstein manifolds T1,1 and Yp,q.