bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study on the Wake Evolution of a Set of RIM-Driven Thrusters
Authors: Gaggero Stefano
Published: August 2023

In the current paper, high-fidelity improved delayed detached-eddy simulations (IDDES) using the OpenFOAM library are employed to characterize the performances and the wake dynamics of RIM-driven thrusters. Despite their relatively old conception, this type of propulsors has gained attention only recently thanks to innovative manufacturing technologies and materials, which finally have made possible their practical implementation. Fostered by stringent regulations on radiated noise and emissions enforced in protected areas, they are also replacing conventional thrusters and main propulsors. By mitigating the tip vortex cavitation and, more in general, by reducing the strength of tip vortices, indeed, these propulsors may grant a reduction in the induced pressure pulses and of the radiated noise without excessively sacrificing the efficiency of the equivalent ducted propellers they replace. To provide proof of this, three different RIM-driven thrusters (one four-bladed, two six-bladed) are analyzed and compared to a reference decelerating ducted propeller delivering the same thrust at identical functioning conditions. The evolution of the trailing wakes of the propulsors, the role of the leakage vortex, and the nozzle wake destabilizing effects, are highlighted, and the superior performances of RIM-driven thrusters, in terms of less intense tip vortices, are discussed. Near-field pressure pulses, as a measure of the radiated noise, are compared, showing a reduction in the sound pressure levels of the selected RIM propulsors up to 15 dB (non-cavitating case) with respect to the reference ducted propeller.
Synergistic Antibiofilm Effects of Exopolymers Produced by the Marine, Thermotolerant Bacillus licheniformis B3-15 and Their Potential Medical Applications
Authors: Zammuto Vincenzo , Agostino Eleonora , Macrì Angela , Spanò Antonio , Grillo Emanuela , Nicolò Marco Sebastiano , Gugliandolo Concetta
Published: August 2023

The exopolysaccharide (EPS B3-15) and biosurfactant (BS B3-15), produced by the marine Bacillus licheniformis B3-15, were recently reported to possess different antibiofilm activities, with the EPS being more active in preventing the adhesion of Pseudomonas aeruginosa and Staphylococcus aureus and the BS in destroying their preformed biofilms on different surfaces. In this study, the synergistic effects of the two exopolymers on the bacterial adhesion and biofilm disruption of P. aeruginosa and S. aureus were evaluated on polystyrene, a medical polyvinyl chloride (PVC) device, and contact lenses (CLs) in order to address their potential use in biomedical applications. To this purpose, EPS B3-15 and BS B3-15 were equally combined (1:1 w/w), and the mixture (BPS B3-15) was added at different concentrations (from 50 to 300 µg mL−1) and at different times of bacterial development. Compared to each polymer, the BPS B3-15 (300 µg mL−1) more efficiently reduced the adhesion of P. aeruginosa and S. aureus on polystyrene (65 and 58%, respectively), PVC devices (62 and 42%, respectively), and CLs (39 and 35%, respectively), also in combination with a CLs care solution (88 and 39%, respectively). Furthermore, BPS B3-15 was able to disrupt mature biofilms, acting more effectively against S. aureus (72%) than P. aeruginosa (6%). The combination of exopolymers at low concentrations exhibited synergistic effects to prevent and eradicate biofilms.
Sea Floor Characterization by Multiples’ Amplitudes in Monochannel Surveys
Authors: Vesnaver Aldo , Baradello Luca
Published: August 2023

The lithological characterization of the seafloor is key information for offshore engineering, especially when it comes to pier and platform design. Undetected shallow gas pockets may cause the collapse of heavy platforms for hydrocarbon production. Unconsolidated sediments are not ideal for the basement of wind farms for electric power production. Drilling and coring can be used for local sampling, but continuous profiles or even areal coverage are far more preferable. High-resolution seismic profiles are successfully used when ports are not too busy, but otherwise, single-channel systems must be used. We show in this paper that even these simpler systems can be used to estimate parameters such as the acoustic impedance of shallow sediments directly beneath the seafloor. We exploit the amplitude decay of the multiple reflections between the seafloor and the surface, which does not depend on the source energy. If the offset between source and receiver is not too small, we can estimate the shallow P velocity and, via acoustic impedance, also the rock density.
Factors Impacting Senior Citizens’ Adoption of E-Banking Post COVID-19 Pandemic: An Empirical Study from India
Authors: Jena Rabindra
Published: August 2023

The global economy and the financial sector have suffered due to the COVID-19 epidemic. The banking industry has seen an increase in digital channels and payments, consumer behavior changes, regulatory and supervisory relief, and new operational resilience challenges due to the COVID-19 pandemic. Therefore, seniors have had to adopt new channels and technologies instead of traditional cash and traditional channels. However, older people in India are not tech-savvy and avoid e-banking. Thus, stakeholders (e.g., bank authorities, governments) must focus on variables affecting the older population’s use of e-banking to reduce financial isolation. Thus, this study uses an extended Unified Theory of Acceptance and Use of Technology (UTAUT) framework to examine senior citizens’ intentions to use e-banking. Data from “456” senior citizens from central India were analyzed using Partial Least Squares Structural Equation Modeling (PLS-SEM) techniques. The study identified different significant predictors (e.g., performance expectancy, effort expectancy, perceived risk, self-efficacy, perceived trust, and anxiety) of older users’ intention to use e-banking post-COVID-19. This is the first study from central India to determine elderly people’s intention to use online banking during and after the COVID-19 pandemic. The findings will help bank authorities and other stakeholders increase senior citizens’ financial inclusion in India.
Interwoven Landscapes: Gender and Land in the Kafue Flats, Zambia
Authors: Merten Sonja , Haller Tobias
Published: August 2023

This paper examines changes in formal and informal land access rules for women in the Kafue Flats of southern Zambia and identifies alternatives to land privatization. In rural African communities dependent on subsistence production, access to common pool resources (CPRs) such as fisheries, wildlife or wild fruits made an important contribution to household food and nutritional security. In the pre-colonial period, the use of agricultural land and associated CPRs was governed by local institutions of common property, characterized by more-than-human relationships embedded in the local animistic ontology. To examine how women’s pre-colonial access rights were increasingly disregarded in the wake of new statutory laws, we analyzed qualitative ethnographic data on livelihoods and food security from three time periods between 2002 and 2018. The findings show how customary law land tenure has remained important, despite being complemented by statutory law designed to also protect women’s property rights. We conclude that women’s customary access rights to land and CPRs must be taken into account in the drafting of formal legislation, as suggested by successful examples of bottom-up institution building in other regions.
Coupling Coordination and Spatiotemporal Analysis of Urban Compactness and Land-Use Efficiency in Resource-Based Areas: A Case Study of Shanxi Province, China
Authors: Chen Yedong , Chang Jiang , Li Zixuan , Ming Li , Li Cankun , Li Cheng
Published: August 2023

Rapid urbanization and industrialization have had a range of effects on urban form and land use, especially in resource-based cities. Previous research has predominantly focused on the analysis of urban compactness or land-use efficiency individually, overlooking their interplay. In this study, we propose a coupled and coordinated research framework for urban compactness (UC) and urban land-use efficiency (ULUE). We analyze the UC and ULUE, as well as the degree and types of coupling and coordination (CCD) between them, in 119 counties and districts rich in coal resources within Shanxi Province. The findings reveal a declining trend in UC in Shanxi Province over time, with coal-resource-based cities exhibiting lower compactness than non-coal-resource-based cities. ULUE has shown stable development during the study period. The CCD between UC and ULUE exhibit spatial and urban typological heterogeneity. Further analysis demonstrates that the CCD types mainly manifest as the lagging development of UC. This research provides a foundation for achieving harmonious development between urban spatial structure and land-use structure and offers new perspectives for the sustainable development of resource-based urban regions.
Advances and Controversies in Acute Alcohol-Related Hepatitis: From Medical Therapy to Liver Transplantation
Authors: Germani Giacomo , D’Arcangelo Francesca , Grasso Marco , Burra Patrizia
Published: August 2023

Alcohol-related hepatitis (AH) is a clinical syndrome characterized by recent-onset jaundice in the context of alcohol consumption. In patients with severe AH “unresponsive” to steroid therapy, mortality rates exceed 70% within six months. According to European and American guidelines, liver transplantation (LT) may be considered in highly selected patients who do not respond to medical therapy. The aim of this narrative review is to summarize current knowledge from medical therapy to liver transplantation in acute alcohol-related hepatitis. Due to the impossibility to guarantee six-month abstinence, LT for AH is controversial. Principal concerns are related to organ scarcity in the subset of stigma of “alcohol use disorder” (AUD) and the risk of relapse to alcohol use after LT. Return to alcohol use after LT is a complex issue that cannot be assessed as a yes/no variable with heterogeneous results among studies. In conclusion, present data indicate that well-selected patients have excellent outcomes, with survival rates of up to 100% at 24 and 36 months after LT. Behavioral therapy, ongoing psychological support, and strong family support seem essential to improve long-term outcomes after LT and reduce the risk in relapse of alcohol use.
New Materials Used for the Development of Anion-Selective Electrodes—A Review
Authors: Wardak Cecylia , Morawska Klaudia , Pietrzak Karolina
Published: August 2023

Ion-selective electrodes are a popular analytical tool useful in the analysis of cations and anions in environmental, industrial and clinical samples. This paper presents an overview of new materials used for the preparation of anion-sensitive ion-selective electrodes during the last five years. Design variants of anion-sensitive electrodes, their advantages and disadvantages as well as research methods used to assess their parameters and analytical usefulness are presented. The work is divided into chapters according to the type of ion to which the electrode is selective. Characteristics of new ionophores used as the electroactive component of ion-sensitive membranes and other materials used to achieve improvement of sensor performance (e.g., nanomaterials, composite and hybrid materials) are presented. Analytical parameters of the electrodes presented in the paper are collected in tables, which allows for easy comparison of different variants of electrodes sensitive to the same ion.
Tungsten–SiO2–Based Planar Field Emission Microtriodes with Different Electrode Topologies
Authors: Avotina Liga , Bikse Liga , Dekhtyar Yuri , Goldmane Annija Elizabete , Kizane Gunta , Muhin Aleksei , Romanova Marina , Smits Krisjanis , Sorokins Hermanis , Vilken Aleksandr , Zaslavskis Aleksandrs
Published: August 2023

This study examines the electrical properties and layer quality of field emission microtriodes that have planar electrode geometry and are based on tungsten (W) and silicon dioxide (SiO2). Two types of microtriodes were analyzed: one with a multi-tip cathode fabricated using photolithography (PL) and the other with a single-tip cathode fabricated using a focused ion beam (FIB). Atomic force microscopy (AFM) analysis revealed surface roughness of the W layer in the order of several nanometers (Ra = 3.8 ± 0.5 nm). The work function values of the Si substrate, SiO2 layer, and W layer were estimated using low-energy ultraviolet photoelectron emission (PE) spectroscopy and were 4.71 eV, 4.85 eV, and 4.67 eV, respectively. The homogeneity of the W layer and the absence of oxygen and silicon impurities were confirmed via X-ray photoelectron spectroscopy (XPS). The PL microtriode and the FIB microtriode exhibited turn-on voltages of 110 V and 50 V, respectively, both demonstrating a field emission current of 0.4 nA. The FIB microtriode showed significantly improved field emission efficiency compared to the PL microtriode, attributed to a higher local electric field near the cathode.
Influence of Manganese Content on Martensitic Transformation of Cu-Al-Mn-Ag Alloy
Authors: Liverić Lovro , Holjevac Grgurić Tamara , Mandić Vilko , Chulist Robert
Published: August 2023

The influence of manganese content on the formation of martensite structure and the final properties of a quaternary Cu-Al-Mn-Ag shape memory alloy (SMA) was investigated. Two alloys with designed compositions, Cu- 9%wt. Al- 16%wt. Mn- 2%wt. Ag and Cu- 9%wt. Al- 7%wt. Mn- 2%wt. Ag, were prepared in an electric arc furnace by melting of high-purity metals. As-cast and quenched microstructures were determined by optical microscopy and scanning electron microscopy equipped with EDS. Phases were confirmed by high-energy synchrotron radiation and electron backscatter diffractions. Austenite and martensite transformations were followed by differential scanning calorimetry and hardness was determined using the Vickers hardness test. It was found that the addition of silver contributes to the formation of the martensite structure in the Cu-Al-Mn-SMA. In the alloy with 7%wt. of manganese, stable martensite is formed even in the as-cast state without additional heat treatment, while the alloy with 16%wt. of manganese martensite transforms only after thermal stabilization and quenching. Two types of martensite, β1′ and γ1′, are confirmed in the Cu-9Al-7Mn-2Ag specimen. The as-cast SMA with 7%wt. Mn showed significantly lower martensite transformation temperatures, Ms and Mf, in relation to the quenched alloy. With increasing manganese content, the Ms and Mf temperatures are shifted to higher values and the microhardness is lower.
The Application of Mott’s Distribution in the Fragmentation of Steel Coaxial Cylinders
Authors: Chiriac Octavian-Gabriel , Bucur Florina , Rotariu Adrian-Nicolae , Trană Eugen
Published: August 2023

This theoretical study analyzes the possibility to use the classical Mott’s hypothesis to model the natural fragmentation of cylindrical structures with two or more metal cylinders arranged coaxially. A critical analysis on the validity of the used hypothesis was conducted based on empirical relations and numerical simulations. The established algorithm allows the determination of a fragment mass scale parameter for each individual cylinder, which is why the cumulative distribution of fragments for the entire structure may be calculated. The results obtained for the structures with two and three cylinders, with equal masses or equal wall thicknesses, can be approximated using a modified Mott’s distribution formula in which the number of cylinders is used as an additional parameter.
Preparation, Chromatic Properties Analysis and Proportioning Optimization of Co-Cr-Fe-Based Black Pigment
Authors: Zhang Weiran , Li Ziyu , Wu Guohua , Wu Wei , Zeng Hailan , Jiang Haiyun , Zhang Weili , Wu Ruomei , Xue Qiong
Published: August 2023

The utilization of Co-Cr-Fe-based black pigments bears considerable significance within the realm of commercial ceramic pigments, owing to their distinctive spinel structure, remarkable high-temperature stability, and exceptional chromatic attributes. This study delves into the synthesis of diverse black pigment configurations by employing the co-precipitation method, leveraging the interplay of these three metallic oxides. This investigation encompasses a comprehensive scrutiny of ion valences, crystal structures and parameters, colorimetric properties, and their interrelationships. The methodology integrates the response surface methodology (RSM) framework, using theoretical formulations to navigate the material ratios and elucidating the associations between the resultant compositions and color coordinate values, aligned with the CIE-Lab* colorimetric methodology. The derived predictive models yielded an optimized black pigment composition, characterized by heightened black intensity and a refined formulation.
A Tunable Frequency Selective Rasorber with Broad Passband and Low Transmission Loss at X-Band
Authors: Shi Shengnan , Chai Zizhao , Zhang Shan , Shi Yanpeng , Zhang Yifei
Published: August 2023

In this paper, we propose a dual-mode frequency selective rasorber (FSR) with tunable transmission and absorption windows at the X-band, which shows a broad passband in each transmission window. The proposed tunable FSR consists of a lossy absorption layer, a lossless transmission layer, and an air gap between them. The top frequency selective surface (FSS) layer is a cross-shaped meandering line with resistors and varactors for tunable absorption, and the bottom layer is a cross-shaped gap with varactors to achieve tunable bandpass. The equivalent circuit model (ECM) is investigated, and the 3D full wave simulation is performed. The results are based on simulations, and the simulation results show that the passband can be tuned from 12 to 8 GHz with an insertion loss between 0.5 and 1.4 dB by sweeping the capacitance of the varactors. The proposed design decreases the chances of detection by adversary devices and assures spectrum-safe communication, thereby creating new avenues for radar stealth and target concealment.
Evolutionary Optimizing Process Parameters in the Induction Hardening of Rack Bar by Response Surface Methodology and Desirability Function Approach under Industrial Conditions
Authors: Dziatkiewicz Grzegorz , Kuska Krzysztof , Popiel Rafał
Published: August 2023

Conditions of industrial production introduce additional complexities while attempting to solve optimization problems of material technology processes. The complexity of the physics of such processes and the uncertainties arising from the natural variability of material parameters and the occurrence of disturbances make modeling based on first principles and modern computational methods difficult and even impossible. In particular, this applies to designing material processes considering their quality criteria. This paper shows the optimization of the rack bar induction hardening operation using the response surface methodology approach and the desirability function. The industrial conditions impose additional constraints on time, cost and implementation of experimental plans, so constructing empirical models is more complicated than in laboratory conditions. The empirical models of nine system responses were identified and used to construct a desirability function using expert knowledge to describe the quality requirements of the hardening operation. An analysis of the hypersurface of the desirability function is presented, and the impossibility of using classical gradient algorithms during optimization is empirically established. An evolutionary strategy in the form of a floating-point encoded genetic algorithm was used, which exhibits a non-zero probability of obtaining a global extremum and is a gradient-free method. Confirmation experiments show the improvement of the process quality using introduced measures.
Hydrophobic, Thermal Shock-and-Corrosion-Resistant XSBR Latex-Modified Lightweight Class G Cement Composites in Geothermal Well Energy Storage Systems
Authors: Sugama Toshifumi , Pyatina Tatiana
Published: August 2023

Energy losses can be significantly reduced if thermally insulating cement is used for energy storage and recovery. The thermal conductivity (TC) of the currently used cement is between 1 and 1.2 W/mK. In this study we assessed the ability of polystyrene (PS)–polybutadiene (PB)–polyacrylic acid (PAA) terpolymer (cross-linked styrene–butadiene rubber, XSBR) latex to improve thermal insulating properties and thermal shock (TS) resistance of class G ordinary Portland cement (OPC) and fly ash cenosphere (FCSs) composites in the temperature range of 100–175 °C. The composites autoclaved at 100 °C were subjected to three cycles, one cycle: 175 °C heat → 25 °C water quenching). In hydrothermal and thermal (TS) environments at elevated temperatures in cement slurries the XSBR latex formed acrylic calcium complexes through acid–base reactions, and the number of such complexes increased at higher temperatures due to the XSBR degradation with formation of additional acrylic groups. As a result, these complexes offered the following five advanced properties to the OPC-based composites: (1) enhanced hydrophobicity; (2) decreased water-fillable porosity; (3) reduced TC for water-saturated composites; (4) minimized loss of compressive strength, Young’s modulus, and compressive fracture toughness after TS; and (5) abated pozzolanic activity of FCSs, which allowed FCSs to persist as thermal insulators under strongly alkaline conditions of cement slurries. Additionally, XSBR-modified slurries possessed improved workability and decreased slurry density due to the air-entraining effect of latex, which resulted in further improvement of thermal insulation performance of the modified composites.
Anti-Condensation Performance of a New Superhydrophobic Coating for Pavements
Authors: Huang Kaijian , Sun Ruiyu , Wang Jiaqing , Shi Xijun , Lei Hechang
Published: August 2023

Superhydrophobic coating ice suppression is an advanced and durable technology that shows great potential for application on pavements. Although many researchers have conducted experimental and theoretical validations to confirm the effectiveness of superhydrophobic surfaces in actively suppressing ice formation, there are still some who remain skeptical. They argue that the roughness of the surface may increase ice adhesion due to the mechanical interlocking effect of condensation droplets in low-temperature and high-humidity environments. In this study, we present a comprehensive investigation of a novel superhydrophobic coating specifically designed for pavement surfaces, aiming to address the question of its active anti-icing/ice-sparing capabilities in a condensing environment. The changes in contact angle before and after condensation for four material surfaces with varying wettability were investigated, as well as the morphology and ice adhesion of liquid water after it freezes on the material surface. The findings reveal that the proposed superhydrophobic coating for pavements effectively prevents condensate droplets from infiltrating the surface structure, resulting in delaying the surface icing time and reducing the attachment strength of the ice.
Diagnostics of Bolted Joints in Vibrating Screens Based on a Multi-Body Dynamical Model
Authors: Krot Pavlo , Shiri Hamid , Dąbek Przemysław , Zimroz Radosław
Published: August 2023

The condition-based maintenance of vibrating screens requires new methods of their elements’ diagnostics due to severe disturbances in measured signals from vibrators and falling pieces of material. The bolted joints of the sieving deck, when failed, require a lot of time and workforce for repair. In this research, the authors proposed the model-based diagnostic method based on modal analysis of the 2-DOF system, which accounts for the interaction of the screen body and the upper deck under conditions of bolted joint degradation. It is shown that the second natural mode with an out-of-phase motion of the upper deck against the main screen housing may coincide with the excitation frequency or its higher harmonics, which appear when vibrators’ bearings are in bad condition. This interaction speeds up bolt loosening and joint opening by the dynamical loading of higher amplitude. The proposed approach can be used to detune the system from resonance and anti-resonance to reduce maintenance costs and energy consumption. To prevent abrupt failures, such parameters as second natural mode frequency, damping factor, and phase space plot (PSP) distortion measures are proposed as bolt health indicators, and these are verified on the laboratory vibrating screen. Also, the robustness is tested by the impulsive non-Gaussian noise addition to the measurement data. A special diagram was proposed for the bolted joints’ strength capacity assessment and maintenance actions planning (tightening, replacement), depending on clearance in the joints.
A Study on Byproducts in the High-Pressure Melamine Production Process
Authors: Walczak Michał , Lemanowicz Marcin , Dziuba Krzysztof , Kubica Robert
Published: August 2023

The industrial production of melamine is carried out by the thermal decomposition of urea in two technological processes, using high or low pressure. The reaction may be accompanied by the formation of undesirable byproducts, oxoaminotriazines, and so-called polycondensates, mainly melam, melem, and melon, as well as their hydrates and adducts. Their presence leads to the deterioration of the quality of the final product and may lead to the release of troublesome deposits inside the apparatus of the product’s separation node. With the limited possibility of controlling the crystallization of the byproducts of the process, improving the technological process requires the precise determination of the composition of the separated insoluble reaction byproducts, which is the main objective of this work. This work presents the results of qualitative and quantitative analyses of the composition of deposits sampled in the technological process of melamine production. The full characterization of the deposits was performed using inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) techniques. The elemental analysis (EA) of carbon, hydrogen, and nitrogen allowed us to obtain characteristic C/H, C/N, and H/N ratios. X-ray diffraction (XRD) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy were also performed to confirm the obtained data. In addition, the morphology of the solid byproducts of the reaction was investigated, and the characteristics of the structures were determined using a scanning electron microscope. The elemental composition was investigated using scanning electron microscopy and the energy-dispersive X-ray spectroscopy (SEM-EDS) technique. The key finding of this research is that about 95% of the deposits are a mixture of melem and melem hydrate. The soluble part of the deposits contains melamine, urea, and oxyaminotriazines, as well as trace inorganic impurities.
Characterization of Composite Freeze-Dried Aerogels with Simulant Lunar Regolith for Space Applications
Authors: Borella Laura , Rozo Andrea , Perfetti Claire , Iorio Carlo Saverio
Published: August 2023

Recently, the goal of space exploration has shifted from the incognito of the solar system to the Moon. Concepts like human permanence on the Moon and thermal protective structures made with ISRU (in situ resource utilization) of raw materials have started to be implemented. By limiting the need to launch supplies from the Earth, the paradigm of spaceflight is changed, privileging the vanguard of the utilisation of resources in situ. Still, the main challenges of surviving the radiation dose and the cryogenic temperatures of the lunar night remain. Recent studies have demonstrated how innovative composite materials can help reduce the temperature stress on exploration vehicles. This research presents the material properties of aerogel insulating materials combined with LHS (lunar highlands simulant) regolith obtained by freeze frying. Organic-based aerogels with different percentages of LHS have been analysed in terms of material, morphology, and thermal properties.
Mechanical Properties Variation in Wood—Plastic Composites with a Mixed Wood Fiber Size
Authors: Xu Hailong , Yang Yang , Li Lifen , Liu Baoyu , Fu Xiubo , Yang Xiaohui , Cao Yan
Published: August 2023

In this study, the influence of fiber particle size on the mechanical properties of a wood-–plastic composite (WPC) was investigated using a combination of experimental measurements and numerical modeling. Four different sizes of wood fibers (10–20 mesh, 20–40 mesh, 40–80 mesh, and 80–120 mesh) were used to reinforce high-density polyethylene (HDPE), either separately or in combination. The different sizes of fibers produced varying properties in the resulting composites. The smallest fiber size (80–120 mesh) resulted in the lowest flexural and tensile properties, but the highest impact strength (15.79 kJ/m2) compared to the other three sizes (12.18–14.29 kJ/m2). Using a blend of fiber sizes resulted in improved mechanical properties. Composites containing a mix of 20–40 mesh and 40–80 mesh fibers exhibited the best flexural (strength 74.16 MPa, modulus 5.35 GPa) and tensile performance (strength 48.27 MPa, modulus 4.30 GPa), while composites containing a mix of all four fiber sizes had the highest impact-resistant strength (16.08 kJ/m2). Several models, including the Rule of Mixtures (ROM), the Inverse Rule of Mixtures (IROM), and the Hirsch models, were used to predict the performance of WPCs. The ROM model was found to be the most accurate in describing the mechanical properties of WPCs reinforced with multi-size wood fibers, based on the sum squared error (SSE) analysis.
Cross-Linking Characteristics, Morphology, Dynamics, and Mechanical and Thermal Properties of Polychloroprene/Polybutadiene/Nano-Zinc (CR/BR/nZn) Compositions with Reduced Fire Hazard
Authors: Smejda-Krzewicka Aleksandra , Rybiński Przemysław , Żukowski Witold , Bradło Dariusz , Wencel Kinga , Berkowicz-Płatek Gabriela
Published: August 2023

The properties of unconventional blends of crystallizable and thermo-cross-linkable polychloroprene (CR) with polybutadiene (BR) were investigated in this study. The compositions were prepared using the method of reactive processing and cross-linking in the presence of nano-sized zinc (nZn). The purpose of the research was to assess the efficacy of nano-zinc as a curing agent of polychloroprene and polybutadiene (CR/BR) composites and to obtain rubber goods characterized by increased flame resistance. The blends were filled with nano-silica (aerosil) and fillers of natural origin (chalcedonite or silitin). The cross-linking process was characterized by determining the kinetics curves, the equilibrium swelling, and the Mooney–Rivlin elasticity constants. The morphology of the vulcanizate surface was specified by scanning electron microscopy (SEM). The dynamic and mechanical properties, flammability, and toxicity of gaseous substances involved in thermal decomposition were determined. Mass changes and thermal effects were studied using simultaneous thermal analysis (STA). It was confirmed that nano-zinc is an efficient curing agent for the polychloroprene and polybutadiene compositions, with a satisfactory degree of cross-linking (αc = 0.10, CRI = 4.11 min−1), good mechanical strength (TSb = 5 MPa), satisfactory tear resistance (Ts = 2.9 N/mm), and very high flame resistance (OI = 30%, HRRmax = 283 kW/m2). Filled products could be used as non-combustible materials, confirming the low fire hazard (1/tflashover = 3.5–6.4 kW/m2∙s). The most effective filler of the tested composites was nano-sized silica.
A Magnetic Field Sensor Based on Directional Coupling in a Magnetic Fluid-Filled Photonic Crystal Fiber
Authors: Liu Yingchao , Zhang Lijun , Ren Shuang , Chen Hailiang
Published: August 2023

In this paper, a dual-core photonic crystal fiber (DC-PCF) sensitivity sensor filled with magnetic liquid is introduced and investigated with the finite element method (FEM). To regulate the energy coupling involving the two cores, the magnetic fluid is filled into the pore between the two cores. To adjust the coupling between the supermodes in the DC-PCF, the refractive index (RI) of the air hole filled magnetic fluid may change due to the external magnetic field. This specifically created a magnetic fluid-filled DC-PCF; the magnetic fluid-filled hole is not used as the core for energy transmission, thus avoiding transmission loss. The dip wavelength and the magnetic field displayed an excellent linear connection between 80 and 260 Oe, depending on the numerical data. The detection sensitivity of the magnetic field reached 515.75 pm/Oe at a short fiber length of 482 µm. The designed magnetic fluid-filled DC-PCF has high sensitivity and small volume and has great application prospects in magnetic field detection in the medical and industrial fields.
Advances in Focused Ion Beam Tomography for Three-Dimensional Characterization in Materials Science
Authors: Mura Francesco , Cognigni Flavio , Ferroni Matteo , Morandi Vittorio , Rossi Marco
Published: August 2023

Over the years, FIB-SEM tomography has become an extremely important technique for the three-dimensional reconstruction of microscopic structures with nanometric resolution. This paper describes in detail the steps required to perform this analysis, from the experimental setup to the data analysis and final reconstruction. To demonstrate the versatility of the technique, a comprehensive list of applications is also summarized, ranging from batteries to shale rocks and even some types of soft materials. Moreover, the continuous technological development, such as the introduction of the latest models of plasma and cryo-FIB, can open the way towards the analysis with this technique of a large class of soft materials, while the introduction of new machine learning and deep learning systems will not only improve the resolution and the quality of the final data, but also expand the degree of automation and efficiency in the dataset handling. These future developments, combined with a technique that is already reliable and widely used in various fields of research, are certain to become a routine tool in electron microscopy and material characterization.
Ag and Sn Implications in 3-Polker Coins Forgeries Evidenced by Nondestructive Methods
Authors: Petean Ioan , Paltinean Gertrud Alexandra , Taut Adrian Catalin , Avram Simona Elena , Pripon Emanoil , Barbu Tudoran Lucian , Borodi Gheorghe
Published: August 2023

Several forged 3-Polker coins have been reported in historical sources on the financial crisis that occurred between 1619 and 1623 at the start of the 30-year-long war. Supposedly, belligerent countries forged other countries’ coins which were then used for external payments as a war strategy. Thus, a lot of 3-Polker coins (e.g., Sigismund-III-type) were forged, and the markets became flooded with poor currency. In the present day, these pre-modern forgeries are rare archeological findings. Only five forged 3-Polker coins randomly found in Transylvania were available for the current study. There are deeper implications of silver and tin in the forgery techniques that need to be considered. Thus, the forged 3-Polker coins were investigated via nondestructive methods: SEM microscopy coupled with EDS elemental spectroscopy for complex microstructural characterization and XRD for phase identification. Three distinct types of forgery methods were identified: the amalgam method is the first used for copper blank silvering (1620), and immersion in melted silver (1621) is the second one. Both methods were used to forge coins with proper legends and inscriptions. The third method is the tin plating of copper coins (with corrupted legend and altered design) (1622, 1623, and 1624). The EDS investigation revealed Hg traces inside the compact silver crusts for the first type and the elongated silver crystallites in the immersion direction, which are well-attached to the copper core for the second type. The third forgery type has a rich tin plating with the superficial formation of Cu6Sn5 compound that assures a good resistance of the coating layer. Therefore, this type should have been easily recognized as fake by traders, while the first two types require proper weighing and margin clipping to ensure their quality.
Design and Control of a Trapezoidal Piezoelectric Bimorph Actuator for Optical Fiber Alignment
Authors: Wang Xinjie , Li Jianhui , Lu Xingfan
Published: August 2023

To align a pair of optical fibers, it is required that the micro actuators used be small and have the characteristics of high accuracy and fast response time. A trapezoidal piezoelectric bimorph actuator was proposed for pushing and pulling an optical fiber. Based on a mathematical model and finite element model established in this paper, we analyzed the output displacement and output force of the proposed trapezoidal piezoelectric actuator under the influence of structural parameters. Since the piezoelectric bimorph actuator had a hysteresis effect, we applied particle swarm optimization to establish a Prandtl–Ishlinskii (PI) model for actuator and parameter identification. Then, two control methods, namely feedforward control considering hysteresis effects and fuzzy proportional-integral-derivative (PID) control employing feedback, were proposed. Finally, a composite control model combining the two control methods with fewer tracking errors was designed. The results show that the output displacement of this actuator is larger than that of a rectangular one. Additionally, the fuzzy PID control has a lower response time (15 ms) and an overshoot (5%).
Modeling the Magnetoelectric Composites in a Wide Frequency Range
Authors: Bichurin Mirza , Sokolov Oleg , Ivanov Sergey , Ivasheva Elena , Leontiev Viktor , Lobekin Vyacheslav , Semenov Gennady
Published: August 2023

This article presents a general theory of the ME effect in composites in the low- and high-frequency ranges. Besides the quasi-static region, the area of electromechanical resonance, including longitudinal, bending, longitudinal shear, and torsional modes, is considered in more detail. To demonstrate the theory, expressions of ME voltage coefficients are obtained for symmetric and asymmetric layered structures. A comparison is made with the experimental results for the GaAs/Metglas and LiNbO3/Metglas structures. The main microwave ME effect, consisting of the FMR line shift in an electric field, for the ferromagnetic metals, their alloys, and YIG ferrite using various piezoelectrics is discussed. In addition to analytical calculations, in the article, finite element modeling is considered. The calculation methods and experimental results are compared for some composites.
Graphs Defined on Rings: A Review
Authors: Madhumitha S. , Naduvath Sudev
Published: August 2023

The study on graphs emerging from different algebraic structures such as groups, rings, fields, vector spaces, etc. is a prominent area of research in mathematics, as algebra and graph theory are two mathematical fields that focus on creating and analysing structures. There are numerous studies linking algebraic structures and graphs, which began with the introduction of Cayley graphs of groups. Several algebraic graphs have been defined on rings, a fast-growing area in the literature. In this article, we systematically review the literature on some variants of Cayley graphs that are defined on rings and highlight the properties and characteristics of such graphs, to showcase the research in this area.
CAM-FRN: Class Attention Map-Based Flare Removal Network in Frontal-Viewing Camera Images of Vehicles
Authors: Kang Seon Jong , Ryu Kyung Bong , Jeong Min Su , Jeong Seong In , Park Kang Ryoung
Published: August 2023

In recent years, active research has been conducted on computer vision and artificial intelligence (AI) for autonomous driving to increase the understanding of the importance of object detection technology using a frontal-viewing camera. However, using an RGB camera as a frontal-viewing camera can generate lens flare artifacts due to strong light sources, components of the camera lens, and foreign substances, which damage the images, making the shape of objects in the images unrecognizable. Furthermore, the object detection performance is significantly reduced owing to a lens flare during semantic segmentation performed for autonomous driving. Flare artifacts pose challenges in their removal, as they are caused by various scattering and reflection effects. The state-of-the-art methods using general scene image retain artifactual noises and fail to eliminate flare entirely when there exist severe levels of flare in the input image. In addition, no study has been conducted to solve these problems in the field of semantic segmentation for autonomous driving. Therefore, this study proposed a novel lens flare removal technique based on a class attention map-based flare removal network (CAM-FRN) and a semantic segmentation method using the images in which the lens flare is removed. CAM-FRN is a generative-based flare removal network that estimates flare regions, generates highlighted images as input, and incorporates the estimated regions into the loss function for successful artifact reconstruction and comprehensive flare removal. We synthesized a lens flare using the Cambridge-driving Labeled Video Database (CamVid) and Karlsruhe Institute of Technology and Toyota Technological Institute at Chicago (KITTI) datasets, which are road scene open datasets. The experimental results showed that semantic segmentation accuracy in images with lens flare was removed based on CAM-FRN, exhibiting 71.26% and 60.27% mean intersection over union (mIoU) in the CamVid and KITTI databases, respectively. This indicates that the proposed method is significantly better than state-of-the-art methods.
Ambrosetti–Prodi Alternative for Coupled and Independent Systems of Second-Order Differential Equations
Authors: Minhós Feliz , Rodrigues Gracino
Published: August 2023

This paper deals with two types of systems of second-order differential equations with parameters: coupled systems with the boundary conditions of the Sturm–Liouville type and classical systems with Dirichlet boundary conditions. We discuss an Ambosetti–Prodi alternative for each system. For the first type of system, we present sufficient conditions for the existence and non-existence of its solutions, and for the second type of system, we present sufficient conditions for the existence and non-existence of a multiplicity of its solutions. Our arguments apply the lower and upper solutions method together with the properties of the Leary–Schauder topological degree theory. To the best of our knowledge, the present study is the first time that the Ambrosetti–Prodi alternative has been obtained for such systems with different parameters.
Industry 4.0: Marvels in Profitability in the Transport Sector
Authors: Bugaj Martin , Durana Pavol , Blazek Roman , Horak Jakub
Published: August 2023

Despite the COVID-19 pandemic, the current era offers the ultimate possibility for prosperous corporate life, especially in the transport sector. Industry 4.0 covers artificial intelligence, big data, or industrial IoT, and thus spatial cognition algorithms, traffic flow prediction, autonomous vehicles, and smart sustainable mobility are not far away. The mentioned tools have already been implemented by enterprises in emerging countries. This exploration focused on transportation within the V4 region from 2016–2021. This article aims to confirm the positive sequel of applying Industry 4.0 to chosen indicators of profitability. The positive, negative, or no shift in the development of 534 businesses was based on Pettitt’s test. The Pearson chi-square test disclosed the significant dependency between Industry 4.0 and shifts in profitability ratios. Then, more than 25% of enterprises involved in Industry 4.0 had positive shifts in ROA, ROC, ROS, and ROR. The research proved not only its balanced effect but also its augmented force through the z-test of proportion. This investigation may provide multiple proofs for connected sectors with transportation to adapt the tools of Industry 4.0 and deliver the call for the governments in the V4 region to make this tool more achievable.
Analytical and Numerical Study of Information Retrieval Method Based on Single-Layer Neural Network with Optimization of Computing Algorithm Performance
Authors: Kostromitin Konstantin , Melnikov Konstantin , Nikonova Dar’ya
Published: August 2023

This work presents a mathematical model of a fast-acting single-layer artificial neural network applied to the task of image reconstruction after noise. For research purposes, this algorithm was implemented in the Python and C++ programming languages. The numerical simulation of the recovery efficiency of the described neural network was performed for different values of the noise factor, the number of samples required to train elements in the sample and the dimensionality of the coupling coefficients, w. The study of the mathematical model of this neural network is presented; as a result, it is possible to identify its essence, to reduce the number of operations required to recover a single element and to increase recovery accuracy by changing the order of calculation of coupling coefficients, w.
Data-Driven Surveillance of Internet Usage Using a Polynomial Profile Monitoring Scheme
Authors: Netshiozwi Unarine , Yeganeh Ali , Shongwe Sandile Charles , Hakimi Ahmad
Published: August 2023

Control charts, which are one of the major tools in the Statistical Process Control (SPC) domain, are used to monitor a process over time and improve the final quality of a product through variation reduction and defect prevention. As a novel development of control charts, referred to as profile monitoring, the study variable is not defined as a quality characteristic; it is a functional relationship between some explanatory and response variables which are monitored in such a way that the major aim is to check the stability of this model (profile) over time. Most of the previous works in the area of profile monitoring have focused on the development of different theories and assumptions, but very little attention has been paid to the practical application in real-life scenarios in this field of study. To address this knowledge gap, this paper proposes a monitoring framework based on the idea of profile monitoring as a data-driven method to monitor the internet usage of a telecom company. By definition of a polynomial model between the hours of each day and the internet usage within each hour, we propose a framework with three monitoring goals: (i) detection of unnatural patterns, (ii) identifying the impact of policies such as providing discounts and, (iii) investigation of general social behaviour variations in the internet usage. The results shows that shifts of different magnitudes can occur in each goal. With the aim of different charting statistics such as Hoteling T2 and MEWMA, the proposed framework can be properly implemented as a monitoring scheme under different shift magnitudes. The results indicate that the MEWMA scheme can perform well in small shifts and has faster detection ability as compared to the Hoteling T2 scheme.