bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Binder Composition and Material Extrusion (MEX) Parameters on the 3D Printing of Highly Filled Copper Feedstocks
Authors: Sadaf Mahrukh , Cano Santiago , Gonzalez-Gutierrez Joamin , Bragaglia Mario , Schuschnigg Stephan , Kukla Christian , Holzer Clemens , Vály Lilla , Kitzmantel Michael , Nanni Francesca
Published: November 2022

This work aims to better understand the type of thermoplastic binders required to produce highly loaded copper filaments that can be successfully printed via low-cost filament-based material extrusion (MEX). Compounding feedstock material with 55 vol.% of copper and three multi-component binder systems has been performed. The MEX behavior of these feedstocks was evaluated by depositing material at different speeds and appropriately selecting the extrusion temperature depending on the binder composition. The rest of the MEX parameters remained constant to evaluate the printing quality for the different feedstocks. Printable filaments were produced with low ovality and good surface quality. The filaments showed good dispersion of the powder and polymeric binder system in SEM analysis. The feedstock mechanical properties, i.e., the tensile strength of the filament, were sufficient to ensure proper feeding in the MEX machine. The viscosity of the feedstock systems at the adjusted printing temperatures lies in the range of 102–103 Pa·s at the shear rate of 100–1000 s−1, which appears to be sufficient to guarantee the correct flowability and continuous extrusion. The tensile properties vary greatly (e.g., ultimate tensile strength 3–9.8 MPa, elongation at break 1.5–40.5%), and the most fragile filament could not be reliably printed at higher speeds. Micrographs of the cross-section of printed parts revealed that as the printing speed increased, the porosity was minimized because the volumetric flow of the feedstock material increased, which can help to fill pores. This study offers new insights into the feedstock requirements needed to produce low-cost intricate copper components of high quality in a reliable and efficient manner. Such components can find many applications in the electronics, biomedical, and many other industries.
Conjugated Polymers Containing EDOT Units as Novel Materials for Electrochromic and Resistance Memory Devices
Authors: He Zipeng , Xu Haoran , Zhang Yuhang , Hou Yanjun , Niu Haijun
Published: November 2022

Four new multifunctional polymers (P1, P2, P3, and P4) containing EDOT units were synthesized by the Stille coupling reaction. A PL spectrum test found that the introduction of large conjugated groups led to strong fluorescence emission in all polymers. Among the electrochromic and switch properties, these polymer films exhibited reversible color changes, as well as good coloring efficiency. Electrochemical experiments found that the initial oxidation potentials of the polymers were 1.27 V, 1.67 V, 1.78 V, and 1.58 V, respectively. Among them, P3 showed a higher coloring efficiency (283.3 cm2·C−1), and P2 showed a shorter response time (tc = 2.2 s, tb = 2.8 s). These polymers all exhibited electrochromic and resistive switching storage characteristics. They have good solubility in many organic solvents. In the resistance switch memory characteristics, all polymers had obvious memristive properties, and P4 exhibited a larger switch current ratio (2527.42) and a smaller threshold voltage (0.9 V).
A Dual-Cavity Fiber Fabry–Pérot Interferometer for Simultaneous Measurement of Thermo-Optic and Thermal Expansion Coefficients of a Polymer
Authors: Lee Cheng-Ling , Ma Chao-Tsung , Yeh Kuei-Chun , Chen Yu-Ming
Published: November 2022

This paper presents a novel method based on a dual-cavity fiber Fabry–Pérot interferometer (DCFFPI) for simultaneously measuring the thermo-optic coefficient (TOC) and thermal expansion coefficient (TEC) of a polymer. The polymer is, by nature, highly responsive to temperature (T) in that its size (length, L) and refractive index (RI, n) are highly dependent on the thermal effect. When the optical length of the polymer cavity changes with T, it is difficult to distinguish whether there is a change in L or n, or both. The variation rates of L and n with a change in T were the TOC and TEC, respectively. Therefore, there was a cross-sensitivity between TOC and TEC in the polymer-based interferometer. The proposed DCFFPI, which cascades a polymer and an air cavity, can solve the above problem. The expansion of the polymer cavity is equal to the compression of the air cavity with the increase in T. By analyzing the individual optical spectra of the polymer and air cavities, the parameters of TOC and TEC can be determined at the same time. The simultaneous measurement of TOC and TEC with small measured deviations of 6 × 10−6 (°C−1) and 3.67 × 10−5 (°C−1) for the polymer NOA61 and 7 × 10−6 (°C−1) and 1.46 × 10−4 (°C−1) for the NOA65 can be achieved. Experimental results regarding the measured accuracy for the class of adhesive-based polymer are presented to demonstrate the feasibility and verify the usefulness of the proposed DCFFPI.
Effects of Polyoxymethylene Fiber on Fresh and Hardened Properties of Seawater Sea-Sand Concrete
Authors: Xue Xuanyi , Wang Fei , Hua Jianmin , Wang Neng , Huang Lepeng , Chen Zengshun , Yao Yunhang
Published: November 2022

Seawater and sea sand are used in concrete to reduce the consumption of freshwater and river sand. To improve the mechanical properties and cracking resistance of concrete, polymer fiber is commonly used. In this study, polyoxymethylene (POM) fiber was innovatively applied to seawater sea-sand concrete (SWSSC), and the workability, early-age cracking behavior, and mechanical properties of SWSSC reinforced with POM fiber were investigated experimentally. A total of 6 kinds of SWSSC mixtures and 72 specimens were included. The test results indicated that with increases in fiber volume fractions (ρ), the workability of SWSSC decreased correspondingly. Compared with plain SWSSC, for SWSSC with ρ = 1%, the decreases in slump and expansibility were 110.6 and 91.9 mm, respectively. POM fiber had a significant enhancing effect on the early-age cracking resistance of SWSSC. Compared with those of plain SWSSC, the cracking indices ac, bc, and cc of the POM-1 specimen decreased by 77.0%, 89.4%, and 97.6%, respectively. Cube and axial compressive tests, splitting tensile tests, and flexural tests were conducted to clarify the effects of POM fiber on the mechanical properties of SWSSC. Compared with plain SWSSC, SWSSC with POM fiber performed better in terms of mechanical properties. Predictive equations were proposed to quantify the effects of POM fiber on the mechanical properties of SWSSC. The failure performances of the SWSSC specimens were discussed and their complete stress–strain curve was analyzed. A stress–strain model for SWSSC was suggested. According to the model, the complete stress–strain curve of SWSSC with any POM fiber content could be determined.
Investigation on Some Algal Extracts as Appropriate Stabilizers for Radiation-Processed Polymers
Authors: Zaharescu Traian , Mateescu Carmen
Published: November 2022

This study presents the appropriate solution, algal extracts, for the improvement of polymer durability when the material is subjected to acute oxidation damage. The investigated support, styrene–isoprene–styrene (SIS), is modified by three algal extracts: Chlorella vulgaris, Spirulina platensis, and Ascophyllum nodosum (Kelp) with a low concentration (1 wt%). The presence of polyhedral oligomeric silsesquioxane (POSS) ensures the growth of stability with respect to the pristine polymer. The thermal performances of the host polymer, indicated by chemiluminescence, reveal the essential contribution of an additive to the improvement in oxidation strength. The stability of the polymer adjusted by algal extracts is proved by the activation energy values, which increase from 49 kJ mol−1 to 89 kJ mol−1 for the same polymer modified with Ascophyllum nodosum. This main important characteristic is the consequence of the highly efficient activity of the polyphenol components of algal extracts and the effect of the three natural additives on the favorably changed kinetic parameters (oxidation induction time and onset oxidation temperature). The exposure of the polymer matrix to the damaging action of γ-rays does not affect the proper contributions to the fast delay in material ageing. The irradiation of 100 kGy, a usual technological dose, may be successfully applied in the radiation processing of a polymer stabilized with algal extracts due to the efficient protection of the additive as the chain-breaking agents.
Macroporous Hyaluronic Acid/Chitosan Polyelectrolyte Complex-Based Hydrogels Loaded with Hydroxyapatite Nanoparticles: Preparation, Characterization and In Vitro Evaluation
Authors: Drozdova Maria G. , Demina Tatiana S. , Dregval Ostap A. , Gaidar Anna I. , Andreeva Elena R. , Zelenetskii Alexander N. , Akopova Tatiana A. , Markvicheva Elena
Published: November 2022

The aim of the study was to fabricate and characterize composite macroporous hydrogels based on a hyaluronic acid/chitosan (Hyal/Ch) polyelectrolyte complex (PEC) loaded with homogeneously distributed hydroxyapatite nanoparticles (nHAp), and to evaluate them in vitro using mouse fibroblasts (L929), osteoblast-like cells (HOS) and human mesenchymal stromal cells (hMSC). Hydrogel morphology as a function of the hydroxyapatite nanoparticle content was studied using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The mean pore size in the Hyal/Ch hydrogel was 204 ± 25 μm. The entrapment of nHAp (1 and 5 wt. %) into the Hyal/Ch hydrogel led to a mean pore size decrease (94 ± 2 and 77 ± 9 μm, relatively). Swelling ratio and weight loss of the hydrogels in various aqueous media were found to increase with an enhancement of a medium ionic strength. Cell morphology and localization within the hydrogels was studied by CLSM. Cell viability depended upon the nHAp content and was evaluated by MTT-assay after 7 days of cultivation in the hydrogels. An increase of the hydroxyapatite nanoparticles loading in a range of 1–10 wt. % resulted in an enhancement of cell growth and proliferation for all hydrogels. Maximum cell viability was obtained in case of the Hyal/Ch/nHAp-10 sample (10 wt. % nHAp), while a minimal cell number was found for the Hyal/Ch/nHAp-1 hydrogel (1 wt. % nHAp). Thus, the proposed simple original technique and the design of PEC hydrogels could be promising for tissue engineering, in particular for bone tissue repair.
Early Modern Uncertainty: Reason, Conscience, and Belief in Post-Reformation Catholicism
Authors: Tutino Stefania
Published: November 2022

This essay investigates the role of uncertainty in post-Reformation Catholicism. It argues that one of the reasons why uncertainty was so central to early modern Catholic discourse lies in the complex and multifaced relationship between believing—that is, the act of holding as true something that we are unable to verify as such by means of reason—and knowing—that is, the act of holding something as true on the basis of a reasonable and reasoned assessment. By providing a brief analysis of printed and manuscript sources, this essays shows how some of the theological, religious, and intellectual tensions in articulating the relationship between things that need to be believed by faith and things that need to be known by reason, both in the works of influential theologians such as Augustine and Francisco Suárez, and in the elaboration of a wider sector of the Catholic population.
Evolution of Korean Megachurch Christianity Intensified by the COVID-19 Pandemic in a Socio-Political Context
Authors: Yoo Kwang Suk
Published: November 2022

This paper examines how megachurch congregations in South Korea responded to governmental measures to control the COVID-19 pandemic in terms of religious governance. This empirical study of Saeronam Church (SC) in Daejeon shows that the unexpected crisis forced its congregants to look back on their faithfulness in terms of self-reflection, and hence, made them more committed to their congregation socially and organizationally. The theologically and politically conservative megachurch congregants tend to regard the pandemic crisis as a God-planned ordeal which must be endured not only through self-reflection and repentance, but also through protection of their congregation from secular authorities. This attitude made it easier for conservative congregants to protest against governmental quarantine measures more explicitly and collectively. While some argue that the COVID-19 pandemic basically accelerated secularity by shrinking religious influence on society, this paper finds this aspect remarkably opposite in Korean conservative churches like SC, and emphasizes how a secular challenge, like the recent quarantine measures, can intensify megachurch Christianity. In this sense, it claims that the second-generation Korean megachurches like SC cannot be explained entirely by traditional theories of urbanization, marketing strategies, and church growth.
Analytical and Native Concepts in Argentina’s Post-Conciliar Catholicism: The Case of “Liberationism”, “Popular Pastoral Theology”, and “Theology of the People”
Authors: Remeseira Claudio Iván
Published: November 2022

“Liberationism”, a term derived from Liberation theology (LT), is an analytical concept used by religious historians and sociologists as a generic designation for Latin American post-conciliar Catholicism. “Theology of the People” (TP) designates a theological school created in Argentina during the late 1960s by the Episcopal Pastoral Commission (COEPAL), although the term used by its members was not TP but “Popular Pastoral theology” (TPp). Successive generations of theologians developed new versions of TPp (“popular piety theology”, “theology of culture”, etc.). I call those versions the diachronic variants of TP, and I regard TP as their synchronic representation. TP has been called the “Argentine School of Liberation Theology”, but there are substantial differences between TP and TL. In this paper, I argue that it is inaccurate to use the term “liberationism” to refer to TP because that term alludes to LT’s model of inter-relations between religion and social change, a model explicitly rejected by the creators of TP. I frame the theoretical discussion on the use of analytical and native concepts in Quentin Skinner’s linguistic contextualism perspective and I explain the differences between TP and TL in the context of the theological–political debates in late-1960s Argentina around the issue of popular Catholicism.
Using Apparent Electrical Conductivity to Delineate Field Variation in an Agroforestry System in the Ozark Highlands
Authors: Ylagan Shane , Brye Kristofor R. , Ashworth Amanda J. , Owens Phillip R. , Smith Harrison , Poncet Aurelie M.
Published: November 2022

Greater adoption and better management of spatially complex, conservation systems such as agroforestry (AF) are dependent on determining methods suitable for delineating in-field variability. However, no work has been conducted using repeated electromagnetic induction (EMI) or apparent electrical conductivity (ECa) surveys in AF systems within the Ozark Highlands of northwest Arkansas. As a result, objectives were to (i) evaluate spatiotemporal ECa variability; (ii) identify ECa-derived soil management zones (SMZs); (iii) establish correlations among ECa survey data and in situ, soil-sensor volumetric water content, sentential site soil-sample EC, and gravimetric water content and pH; and (iv) determine the optimum frequency at which ECa surveys could be conducted to capture temporal changes in field variability. Monthly ECa surveys were conducted between August 2020 and July 2021 at a 4.25 ha AF site in Fayetteville, Arkansas. The overall mean perpendicular geometry (PRP) and horizontal coplanar geometry (HCP) ECa ranged from 1.8 to 18.0 and 3.1 to 25.8 mS m−1, respectively, and the overall mean HCP ECa was 67% greater than the mean PRP ECa. The largest measured ECa values occurred within the local drainage way or areas of potential groundwater movement, and the smallest measured ECa values occurred within areas with decreased effective soil depth and increased coarse fragments. The PRP and HCP mean ECa, standard deviation (SD), and coefficient of variation (CV) were unaffected (p > 0.05) by either the weather or growing/non-growing season. K-means clustering delineated three precision SMZs that were reflective of areas with similar ECa and ECa variability. Results from this study provided valuable information regarding the application of ECa surveys to quantify small-scale changes in soil properties and delineate SMZs in highly variable AF systems.
Remote Sensing Image Super-Resolution via Residual-Dense Hybrid Attention Network
Authors: Yu Bo , Lei Bin , Guo Jiayi , Sun Jiande , Li Shengtao , Xie Guangshuai
Published: November 2022

Nowadays, remote sensing datasets with long temporal coverage generally have a limited spatial resolution, most of the existing research uses the single image super-resolution (SISR) method to reconstruct high-resolution (HR) images. However, due to the lack of information in low-resolution (LR) images and the ill-posed nature of SISR, it is difficult to reconstruct the fine texture of HR images under large-scale magnification factors (e.g., four times). To address this problem, we propose a new reference-based super-resolution method called a Residual-Dense Hybrid Attention Network (R-DHAN), which uses the rich texture information in the reference image to make up for the deficiency of the original LR image. The proposed SR model employs Super-Resolution by Neural Texture Transfer (SRNTT) as a backbone. Based on this structure, we propose a dense hybrid attention block (DHAB) as a building block of R-DHAN. The DHAB fuses the input and its internal features of current block. While making full use of the feature information, it uses the interdependence between different channels and different spatial dimensions to model and obtains a strong representation ability. In addition, a hybrid channel-spatial attention mechanism is introduced to focus on important and useful regions to better reconstruct the final image. Experiments show that compared with SRNTT and some classical SR techniques, the proposed R-DHAN method performs well in quantitative evaluation and visual quality.
Analyzing Satellite-Derived 3D Building Inventories and Quantifying Urban Growth towards Active Faults: A Case Study of Bishkek, Kyrgyzstan
Authors: Watson C. Scott , Elliott John R. , Amey Ruth M. J. , Abdrakhmatov Kanatbek E.
Published: November 2022

Earth observation (EO) data can provide large scale, high-resolution, and transferable methodologies to quantify the sprawl and vertical development of cities and are required to inform disaster risk reduction strategies for current and future populations. We synthesize the evolution of Bishkek, Kyrgyzstan, which experiences high seismic hazard, and derive new datasets relevant for seismic risk modeling. First, the urban sprawl of Bishkek (1979–2021) was quantified using built-up area land cover classifications. Second, a change detection methodology was applied to a declassified KeyHole Hexagon (KH-9) and Sentinel-2 satellite image to detect areas of redevelopment within Bishkek. Finally, vertical development was quantified using multi-temporal high-resolution stereo and tri-stereo satellite imagery, which were used in a deep learning workflow to extract buildings footprints and assign building heights. Our results revealed urban growth of 139 km2 (92%) and redevelopment of ~26% (59 km2) of the city (1979–2021). The trends of urban growth were not reflected in all the open access global settlement footprint products that were evaluated. Building polygons that were extracted using a deep learning workflow applied to high-resolution tri-stereo (Pleiades) satellite imagery were most accurate (F1 score = 0.70) compared to stereo (WorldView-2) imagery (F1 score = 0.61). Similarly, building heights extracted using a Pleiades-derived digital elevation model were most comparable to independent measurements obtained using ICESat-2 altimetry data and field-measurements (normalized absolute median deviation < 1 m). Across different areas of the city, our analysis suggested rates of building growth in the region of 2000–10,700 buildings per year, which when combined with a trend of urban growth towards active faults highlights the importance of up-to-date building stock exposure data in areas of seismic hazard. Deep learning methodologies applied to high-resolution imagery are a valuable monitoring tool for building stock, especially where country-level or open-source datasets are lacking or incomplete.
An Indoor Tracking Algorithm Based on Particle Filter and Nearest Neighbor Data Fusion for Wireless Sensor Networks
Authors: Cheng Long , Zhang Hao , Wei Dacheng , Zhou Jiabao
Published: November 2022

Wireless indoor localization technology is a hot research field at present. Its basic principle is to estimate the geometric position of the mobile node by measuring the characteristic parameters of the propagation signal between the mobile node and the beacon node. However, in the process of position estimation, there are non-line-of-sight errors such as multipath propagation, which greatly reduces the localization accuracy. This paper proposes an enhanced closest neighbor data association approach based on ultra-wide band (UWB) measurement. First, the measured values were grouped to obtain a series of undetermined prediction position points, and the undetermined points were put into our set verification gate for screening. Then, the particle filter was introduced to weight and redistribute the position estimation after screening, removing the NLOS-contaminated location estimation from consideration. The position estimation group with low error was finally confirmed and weighted again by the nearest neighbor association algorithm. Simulation results showed that the average localization accuracy of the proposed method was about 1 m. Compared with the existing localization algorithms, the proposed method can successfully reduce the influence of NLOS error and obtain higher localization accuracy.
Using the Geodetector Method to Characterize the Spatiotemporal Dynamics of Vegetation and Its Interaction with Environmental Factors in the Qinba Mountains, China
Authors: Zhang Shuhui , Zhou Yuke , Yu Yong , Li Feng , Zhang Ruixin , Li Wenlong
Published: November 2022

Understanding the driving mechanisms of vegetation development is critical for maintaining terrestrial ecosystem function in mountain areas, especially under the background of climate change. The Qinba Mountains (QBM), a critical north–south transition zone in China, is an environmentally fragile area that is vulnerable to climate change. It is essential to characterize how its ecological environment has changed. Currently, such a characterization remains unclear in the spatiotemporal patterns of the nonlinear effects and interactions between environmental factors and vegetation changes in the QBM. Here, we utilized the Normalized Difference Vegetation Index (NDVI), obtained from Google Earth Engine (GEE) platform, as an indicator of terrestrial ecosystem conditions. Then, we measured the spatiotemporal heterogeneity for vegetation variation in the QBM from 2003 to 2018. Specifically, the Geodetector method, a new geographically statistical method without linear assumptions, was employed to detect the interaction between vegetation and environmental driving factors. The results indicated that there is a trend of a general increase in vegetation growth amplitude (the average NDVI increased from 0.810 to 0.858). The areas with an NDVI greater than 0.8 are mainly distributed in the Qinling Mountains and the Daba Mountains, which account for more than 76.39% of the QBM area. For the entire region, the global Moran’s index of the NDVI is greater than 0.95, indicating that vegetation is highly concentrated in the spatial domain. The Geodetector identified that landform type was the primary factor in controlling vegetation changes, contributing 24.19% to the total variation, while the explanatory powers of the aridity index and the wetness index for vegetation changes were 22.49% and 21.47%, respectively. Furthermore, the interaction effects between any two factors outperformed the influence of a single environmental variable. The interaction between air temperature and the aridity index was the most significant element, contributing to 47.10% of the vegetation variation. These findings can not only improve our understanding in the interactive effects of environmental forces on vegetation change, but also be a valuable reference for ecosystem management in the QBM area, such as ecological conservation planning and the assessment of ecosystem functions.
Imperceptible Flicker Noise Reduction Using Pseudo-Flicker Weight Functionalized Derivative Equalization in Light-Fidelity Transmission Link
Authors: Won Yong-Yuk , Kang Jeungmo
Published: November 2022

A new technique to reduce flicker noise generated in light-fidelity (Li-Fi) transmission links based on the white light-emitting diode (LED) is proposed. Here, flicker noise with a frequency of 120 Hz, which is twice the frequency of AC power (60 Hz), is generated. The proposed technique is implemented in the receiver of the Li-Fi link. It can reduce flicker noise regardless of various digital modulation formats. In addition, there is no need to change the structure of the electrical circuit driving the LED to reduce the flicker noise. As a result, the non-return to-zero-on-off-keying (NRZ–OOK) signal waveform is tilted according to the flicker noise waveform. We implement the derivative equalization with a pseudo-flicker weight function to reduce the flicker noise. The derivative value of the NRZ–OOK signal mixed with flicker noise becomes larger than that without the flicker noise. In the proposed technique, the derivative value between adjacent sampling points is suppressed below the preset thresholds when it is greater than the preset threshold. Furthermore, a pseudo-flicker weight function is applied to accelerate the flicker noise reduction. As a result, using the proposed technique, a 2 dB signal-to-noise ratio (SNR) gain is obtained based on the bit error rate (BER) threshold (3.5 × 10−5) corresponding to 10% flicker modulation, which is known to have no serious effect on human health. This means that it is possible to implement a Li-Fi transmission link based on an illumination environment with a flicker modulation reduced from 10% to 7%.
LiDAR and Deep Learning-Based Standing Tree Detection for Firebreaks Applications
Authors: Liu Zhiyong , Wang Xi , Zhu Jiankai , Cheng Pengle , Huang Ying
Published: November 2022

Forest fire prevention is very important for the protection of the ecological environment, which requires effective prevention and timely suppression. The opening of the firebreaks barrier contributes significantly to forest fire prevention. The development of an artificial intelligence algorithm makes it possible for an intelligent belt opener to create the opening of the firebreak barrier. This paper introduces an innovative vision system of an intelligent belt opener to monitor the environment during the creation of the opening of the firebreak barrier. It can provide precise geometric and location information on trees through the combination of LIDAR data and deep learning methods. Four deep learning networks including PointRCNN, PointPillars, SECOND, and PV-RCNN were investigated in this paper, and we train each of the four networks using our stand tree detection dataset which is built on the KITTI point cloud dataset. Among them, the PointRCNN showed the highest detection accuracy followed by PV-RCNN and PV-RCNN. SECOND showed less detection accuracy but can detect the most targets.
Design of a 5G Sub-6 GHz Vehicular Cellular Antenna Element with Consistent Radiation Pattern Using Characteristic Mode Analysis
Authors: Abdul-Rahman Ehab , Aloi Daniel N.
Published: November 2022

A cellular 5G sub-6 GHz vehicle antenna design with a consistent radiation pattern across the frequency bands in 0.617–5 GHz is demonstrated via characteristic mode analysis. The design focuses on maintaining monopole first-order mode radiation pattern over cellular frequency bands and avoiding higher-order modes out of the operational frequency bands to provide optimal performance for automotive requirements. Rather than using an empirical design method, the design procedure in this paper uses the calculated modal significance, characteristic current, modal radiation pattern, and reflection coefficient to define the antenna structure dimensions. The proposed design was simulated, a prototype was measured, and the performance was evaluated on a 1-m ground plane. The antenna has perfect omnidirectionality with a high and stable gain across the frequency range in the 30° area above the horizon.
Design and Analysis of the Capacitive RF MEMS Switches with Support Pillars
Authors: Feng Hongbo , Zhao Jiabin , Zhou Chengsi , Song Mingxin
Published: November 2022

Conventional parallel capacitive RF MEMS switches have a large impact during the suction phase. In general, RF MEMS switches have to be switched on and off in a considerably fast manner. Increasing the driving voltage enables fast switching but also increases the impact force, which causes the beam membrane to be prone to failure. In the present study, the addition of two support pillars was proposed for slowing down the fall of the beam membrane based on the conventional RF MEMS parallel switch, so as to reduce the impact velocity. As such, a novel RF MEMS switch was designed. Further, simulation software was used to scan and analyze the positioning and height of the support pillars with respect to electromechanical and electromagnetic performance. The simulation results show that the optimal balance of impact velocity and pull-in time was achieved at a height of 0.8 um, a distance of 10 um from the signal line, and an applied voltage of 50 V. The impact velocity was reduced from 1.8 m/s to 1.1 m/s, decreasing by nearly 40%. The turn off time increased from 3.9 us to 4.2 us, representing an increase of only 0.05%. The insertion loss was less than 0.5 dB at 32 GHz, and the isolation was greater than 50 dB at 40 GHz.
Guidance, Navigation and Control for Autonomous Quadrotor Flight in an Agricultural Field: The Case of Vineyards
Authors: Mokrane Adel , Benallegue Abdelaziz , Choukchou-Braham Amal , El Hadri Abdelhafid , Cherki Brahim
Published: November 2022

In this paper, we present a complete and efficient solution of guidance, navigation and control for a quadrotor platform to accomplish 3D coverage flight missions in mapped vineyard terrains. Firstly, an occupancy grid map of the terrain is used to generate a safe guiding coverage path using an Iterative Structured Orientation planning algorithm. Secondly, way-points are extracted from the generated path and added to them trajectory’s velocities and accelerations constraints. The constrained way-points are fed into a Linear Quadratic Regulator algorithm so as to generate global minimum snap optimal trajectory while satisfying both the pointing and the corridor constraints. Then, when facing unexpected obstacles, the quadrotor tends to re-plan its path in real-time locally using an Improved Artificial Potential Field algorithm. Finally, a geometric trajectory tracking controller is developed on the Special Euclidean group SE(3). The aim of this controller is to track the generated trajectory while pointing towards predetermined direction using the vector measurements provided by the inertial unit. The performance of the proposed method is demonstrated through several simulation results. In particular, safe guiding paths are achieved. Obstacle-free optimal trajectories that satisfy the way-point position, the pointing direction, and the corridor constraints, are successfully generated with optimized platform snap. Besides, the implemented geometric controller can achieve higher trajectory tracking accuracy with an absolute value of the maximum error in the order of 10−3 m.
Fiber Bragg Grating Sensors for Reinforcing Bar Slippage Detection and Bond-Slip Gradient Characterization
Authors: Pereira Luis , Mesquita Esequiel , Alberto Nélia , Melo José , Marques Carlos , Antunes Paulo , André Paulo S. , Varum Humberto
Published: November 2022

The detection of bond-slip between the reinforcing bar (RB) and concrete is of great importance to ensure the safety of reinforced concrete (RC) structures. The techniques to monitor the connection between the RB and concrete are in constant development, with special focus on the ones with straightforward operation and simple non-intrusive implementation. In this work, a simple configuration is developed using 10 optical fiber sensors, allowing different sections of the same RC structure to be monitored. Since the RB may suffer different strains along its length, the location of the sensors is critical to provide an early warning about any displacement. Bragg gratings were inscribed in both silica and polymer optical fibers and these devices worked as displacement sensors by monitoring the strain variations on the fibers. The results showed that these sensors can be easily implemented in a civil construction environment, and due to the small dimensions, they can be a non-intrusive technique when multiple sensors are implemented in the same RC structure.
Output Characterization of 220 nm Broadband 1250 nm Wavelength-Swept Laser for Dynamic Optical Fiber Sensors
Authors: Lee Gi Hyen , Ahn Soyeon , Kim Min Su , Lee Sang Won , Kim Ji Su , Choi Byeong Kwon , Pagidi Srinivas , Jeon Min Yong
Published: November 2022

Broadband wavelength-swept lasers (WSLs) are widely used as light sources in biophotonics and optical fiber sensors. Herein, we present a polygonal mirror scanning wavelength filter (PMSWF)-based broadband WSL using two semiconductor optical amplifiers (SOAs) with different center wavelengths as the gain medium. The 10-dB bandwidth of the wavelength scanning range with 3.6 kHz scanning frequency was approximately 223 nm, from 1129 nm to 1352 nm. When the scanning frequency of the WSL was increased, the intensity and bandwidth decreased. The main reason for this is that the laser oscillation time becomes insufficient as the scanning frequency increases. We analyzed the intensity and bandwidth decrease according to the increase in the scanning frequency in the WSL through the concept of saturation limit frequency. In addition, optical alignment is important for realizing broadband WSLs. The optimal condition can be determined by analyzing the beam alignment according to the position of the diffraction grating and the lenses in the PMSWF. This broadband WSL is specially expected to be used as a light source in broadband distributed dynamic FBG fiber-optic sensors.
Optimizing Color-Difference Formulas for 3D-Printed Objects
Authors: Huang Min , Gao Xinyuan , Pan Jie , Li Xiu , Hemingray Caroline , Xiao Kaida , Melgosa Manuel
Published: November 2022

Based on previous visual assessments of 440 color pairs of 3D-printed samples, we tested the performance of eight color-difference formulas (CIELAB, CIEDE2000, CAM02-LCD, CAM02-SCD, CAM02-UCS, CAM16-LCD, CAM16-SCD, and CAM16-UCS) using the standardized residual sum of squares (STRESS) index. For the whole set of 440 color pairs, the introduction of kL (lightness parametric factor), b (exponent in total color difference), and kL + b produced an average STRESS decrease of 2.6%, 26.9%, and 29.6%, respectively. In most cases, the CIELAB formula was significantly worse statistically than the remaining seven formulas, for which no statistically significant differences were found. Therefore, based on visual results using 3D-object colors with the specific shape, size, gloss, and magnitude of color differences considered here, we concluded that the CIEDE2000, CAM02-, and CAM16-based formulas were equivalent and thus cannot recommend only one of them. Disregarding CIELAB, the average STRESS decreases in the kL + b-optimized formulas from changes in each one of the four analyzed parametric factors were not statistically significant and had the following values: 6.2 units changing from color pairs with less to more than 5.0 CIELAB units; 2.9 units changing the shape of the samples (lowest STRESS values for cylinders); 0.7 units changing from nearly-matte to high-gloss samples; and 0.5 units changing from 4 cm to 2 cm samples.
Demand Response Contextual Remuneration of Prosumers with Distributed Storage
Authors: Silva Cátia , Faria Pedro , Ribeiro Bruno , Gomes Luís , Vale Zita
Published: November 2022

Prosumers are emerging in the power and energy market to provide load flexibility to smooth the use of distributed generation. The volatile behavior increases the production prediction complexity, and the demand side must take a step forward to participate in demand response events triggered by a community manager. If balance is achieved, the participants should be compensated for the discomfort caused. The authors in this paper propose a methodology to optimally manage a community, with a focus on the remuneration of community members for the provided flexibility. Four approaches were compared and evaluated, considering contextual tariffs. The obtained results show that it was possible to improve the fairness of the remuneration, which is an incentive and compensation for the loss of comfort. The single fair remuneration approach was more beneficial to the community manager, since the total remuneration was lower than the remaining approaches (163.81 m.u. in case study 3). From the prosumers’ side, considering a clustering method was more advantageous, since higher remuneration was distributed for the flexibility provided (196.27 m.u. in case study 3).
Computer Vision Based Pothole Detection under Challenging Conditions
Authors: Bučko Boris , Lieskovská Eva , Zábovská Katarína , Zábovský Michal
Published: November 2022

Road discrepancies such as potholes and road cracks are often present in our day-to-day commuting and travel. The cost of damage repairs caused by potholes has always been a concern for owners of any type of vehicle. Thus, an early detection processes can contribute to the swift response of road maintenance services and the prevention of pothole related accidents. In this paper, automatic detection of potholes is performed using the computer vision model library, You Look Only Once version 3, also known as Yolo v3. Light and weather during driving naturally affect our ability to observe road damage. Such adverse conditions also negatively influence the performance of visual object detectors. The aim of this work was to examine the effect adverse conditions have on pothole detection. The basic design of this study is therefore composed of two main parts: (1) dataset creation and data processing, and (2) dataset experiments using Yolo v3. Additionally, Sparse R-CNN was incorporated into our experiments. For this purpose, a dataset consisting of subsets of images recorded under different light and weather was developed. To the best of our knowledge, there exists no detailed analysis of pothole detection performance under adverse conditions. Despite the existence of newer libraries, Yolo v3 is still a competitive architecture that provides good results with lower hardware requirements.
A New SCAE-MT Classification Model for Hyperspectral Remote Sensing Images
Authors: Chen Huayue , Chen Ye , Wang Qiuyue , Chen Tao , Zhao Huimin
Published: November 2022

Hyperspectral remote sensing images (HRSI) have the characteristics of foreign objects with the same spectrum. As it is difficult to label samples manually, the hyperspectral remote sensing images are understood to be typical “small sample” datasets. Deep neural networks can effectively extract the deep features from the HRSI, but the classification accuracy mainly depends on the training label samples. Therefore, the stacked convolutional autoencoder network and transfer learning strategy are employed in order to design a new stacked convolutional autoencoder network model transfer (SCAE-MT) for the purposes of classifying the HRSI in this paper. In the proposed classification method, the stacked convolutional au-to-encoding network is employed in order to effectively extract the deep features from the HRSI. Then, the transfer learning strategy is applied to design a stacked convolutional autoencoder network model transfer under the small and limited training samples. The SCAE-MT model is used to propose a new HRSI classification method in order to solve the small samples of the HRSI. In this study, in order to prove the effectiveness of the proposed classification method, two HRSI datasets were chosen. In order to verify the effectiveness of the methods, the overall classification accuracy (OA) of the convolutional self-coding network classification method (CAE), the stack convolutional self-coding network classification method (SCAE), and the SCAE-MT method under 5%, 10%, and 15% training sets are calculated. When compared with the CAE and SCAE models in 5%, 10%, and 15% training datasets, the overall accuracy (OA) of the SCAE-MT method was improved by 2.71%, 3.33%, and 3.07% (on average), respectively. The SCAE-MT method is, thus, clearly superior to the other methods and also shows a good classification performance.
Sensory Interaction and Balancing Ability Evaluation of the Elderly Using a Simplified Force Plate System
Authors: Seo Jeong-Woo , Kim Joong Il , Kim Taehong , Jang Kyoung-Mi , Jeong Youngjae , Do Jun-Hyeong
Published: November 2022

The Wii balance board (WBB) is a simplified force plate system used to evaluate the balancing ability of the elderly via a sensory interaction task to confirm a significant standing balance index. The accuracy of this system has been verified in previous studies. In this study, an instrumented and modified clinical test of sensory interaction on balance (i-mCTSIB) was performed on 84 elderly subjects, and the variables for center of pressure (CoP) were calculated using WBB for each task condition. The results indicate that the visual condition has a significant effect on the sway proprioceptive sensory variables with a foam condition as their complexity increases. In addition, the correlation between the variable and Berg Balance Scale was not confirmed since CTSIB is a sensory interaction on balance ability. Therefore, WBB can be used to evaluate balancing ability based on sensory interactions consisting of the surface condition.
The Job Performance of Fly-In-Fly-Out Workers in Industrial Enterprises (on the Example of Oil and Gas Production, Diamond Mining Production, and Construction)
Authors: Korneeva Yana
Published: November 2022

With high health requirements for FIFO work at industry, workers may experience adverse changes in psychological well-being and health status. This makes it relevant when developing the job performance model to rely on considering not only the effectiveness by employees but also their psychophysiological “cost of activity”, which is not reflected in modern scientific research. This article theoretically substantiates and empirically develops a job performance typology of fly-in-fly-out workers at industrial enterprises by correlating three components: effectiveness, psychophysiological resources, and the way of accomplishing tasks. The study involved 359 fly-in-fly-out workers in oil and gas, diamond mining and construction industries with different duration of the fly-in period, operating in the South and the North of the Russian Federation. The research methods included questioning, psychophysiological instrumental testing, and psychological testing. Statistical processing was carried out using the methods of descriptive statistics, two-stage cluster analysis, and multivariate analysis of variance. As a result of the study, six types of job performance of fly-in-fly-out personnel of industrial enterprises were identified. The employees at industrial enterprises of all six types of job performance correspond to their position and perform the assigned tasks, the difference in them lies in the desire to show an average or the highest possible result, as well as how much internal resources the employee spends to achieve this result and how quickly he restores them, which is expressed in terms of his state and well-being. Based on the results of these connections, measures for personnel management for industrial enterprises were proposed.
Psychosocial Impact of the COVID-19 Pandemic on Healthcare Professionals in Spain
Authors: Magro Ana , Gutiérrez-García Aida , González-Álvarez Marta , Del Líbano Mario
Published: November 2022

In December 2019, a new virus called SARS-CoV-2 appeared, and the disease it produced was named COVID-19. After the pandemic situation was declared by the World Health Organization in March 2020, an increasing worsening of the mental health of the population, especially healthcare professionals, became apparent. To determine the psychosocial impact of the pandemic on healthcare professionals in Spain, a longitudinal study was conducted at two time points separated by 5 weeks (n time 1 = 169; n time 2 = 65). Participants completed an online questionnaire assessing depression, anxiety, and stress (Depression Anxiety Stress Scale, DASS-21), burnout (Maslach Burnout Inventory—MBI), resilience (Brief Resilience Scale—BRS), and health-related quality of life (SF-36 Health Questionnaire). The results showed high levels of depression, anxiety, stress, and burnout, as well as moderate levels of resilience and low levels of quality of life at the first assessment. Resilience was negatively related to negative experiences, and positively related to the quality of life, also at the first assessment. Overall, there was an improvement in the mental health of healthcare professionals when comparing the two assessments. In this improvement, having COVID-19 in the first assessment had a positive effect on perceived mental health in the second assessment.
Climate Change and Impact on Renewable Energies in the Azores Strategic Visions for Sustainability
Authors: Meirelles Maria , Carvalho Fernanda , Porteiro João , Henriques Diamantino , Navarro Patrícia , Vasconcelos Helena
Published: November 2022

The energy sector is the largest contributor to global greenhouse gas emissions, but could also be seriously affected by climate change, calling into question society’s current consumption patterns. In this communication, climate projections based on a set of numerical models of global circulation are used to simulate the climate until the end of the century and keep in mind the alternative scenarios of pollutant emissions. Apart from solar energy, the results for the Azores region show a negative impact on the production and consumption of renewable energies. In the regional context, this issue assumes special relevance, given the geographical constraints, such as territorial discontinuity and insularity. Based on these assumptions, measures and recommendations are pointed out for the sectors that most penalize greenhouse gas emissions, considering the energy sustainability in the Azores and the commitments and goals assumed under international agreements.