bluuebunny/crossref_metadata_2025 huggingface dataset:
Embryonic and Larval Development of Stinging Catfish, Heteropneustes fossilis, in Relation to Climatic and Water Quality Parameters
Authors: Mahalder Balaram , Haque Mohammad Mahfujul , Siddique Mohammad Abu Baker , Hasan Neaz A. , Alam Md. Mehedi , Talukdar Md. Mahamudun Naby , Shohan Mobin Hossain , Ahasan Nusaifa , Hasan Md. Mahmudul , Ahammad A. K. Shakur
Published: February 2023

In terms of hatchery-based seed production, one of the most important aquaculture species in Bangladesh is the stinging catfish (Heteropneustes fossilis). Scientific and evidence-based embryonic and larval development research on this fish species in the context of climate change is limited. This experimental study was conducted via induced breeding of stinging catfish using a conventional hatchery system, rearing the larvae in hapas placed in ponds. A series of microscopic observations using a trinocular digital microscope and an analysis of the relationship between larval growth and climate-driven water quality parameters such as temperature, pH, dissolved oxygen, total dissolved solids, alkalinity, and ammonia were performed. During embryonic development, the first cleavage was observed between 30 and 35 min of post-fertilization. Embryonic development (ranging from the 2-cell to the pre-hatching stage) took 21:00 h. Hatching occurred at 22:30 to 23:00 h after fertilization, with an average larvae length of 2.78 ± 0.04 mm. In the post-hatching stage, four pairs of tiny barbels appeared at 36:00 h, and the larvae started feeding exogenously after 72:00 h. These larvae fully absorbed their yolk sacs on the 6th day and attained an average length of 6.44 ± 0.06 mm. Aerial respiration of the larvae was investigated through naked-eye observation on the 10th day of hatching. The average length of the larvae was 32.00 ± 2.0 mm at the end of the 30-day post-hatching observation period. Bivariate correlation analysis showed significant correlations between key climatic variables and water quality parameters under hapa-based larval-rearing conditions. According to canonical correlation analysis, the first canonical function revealed the highest significant correlation between the two sets of variables (r1 = 0.791). The response variable weight of larvae (6.607) was linked to two explanatory variables: pH (0.321) and dissolved oxygen (0.265). For the second canonical correlation function, a positive correlation (0.431) was observed between the two sets of variables. Larval weight (−18.304) was observed to be linked to climatic variables, including air temperature (−0.316) and surface pressure (0.338). Results of this study reveal the subtle correlation between larval growth and water quality driven by climatic variables.
Understanding COVID: Collaborative Government Campaign for Citizen Digital Health Literacy in the COVID-19 Pandemic
Authors: López-Ventoso Mónica , Pisano González Marta , Fernández García Cristina , Diez Valcarce Isabel , Rey Hidalgo Inés , Rodríguez Nachón María Jesús , Menéndez García Ana María , Perello Michelle , Avagnina Beatrice , Zanutto Oscar , Lana Alberto
Published: February 2023

The strategy “Understanding COVID” was a Public Health campaign designed in 2020 and launched in 2021 in Asturias-Spain to provide reliable and comprehensive information oriented to vulnerable populations. The campaign involved groups considered socially vulnerable and/or highly exposed to COVID-19 infection: shopkeepers and hoteliers, worship and religious event participants, school children and their families, and scattered rural populations exposed to the digital divide. The purpose of this article was to describe the design of the “Understanding COVID” strategy and the evaluation of the implementation process. The strategy included the design and use of several educational resources and communication strategies, including some hundred online training sessions based on the published studies and adapted to the language and dissemination approaches, that reached 1056 people of different ages and target groups, an accessible website, an informative video channel, posters and other pedagogical actions in education centers. It required a great coordination effort involving different public and third-sector entities to provide the intended pandemic protection and prevention information at that difficult time. A communication strategy was implemented to achieve different goals: reaching a diverse population and adapting the published studies to different ages and groups, focusing on making it comprehensible and accessible for them. In conclusion, given there is a common and sufficiently important goal, it is possible to achieve effective collaboration between different governmental bodies to develop a coordinated strategy to reach the most vulnerable populations while taking into consideration their different interests and needs.
β Grain Size Inhomogeneity of Large Scale Ti-5Al-5V-5Mo-3Cr Alloy Bulk after Multi-Cycle and Multi-Axial Forging in α + β Field
Authors: Qin Dongyang , Liu Huifang , Li Yulong
Published: February 2023

In order to fabricate homogeneous large-scale Ti-5Al-5V-5Mo-3Cr (Ti-5553) alloy bulk with fine and equiaxial β grain, we performed a series of multi-axial α + β field forging with 62 forging cycles on the large-scale Ti-5553 billet by using 12.5 MN high-speed hydraulic press. The β-annealed microstructure was the starting microstructure of the billet. After the 6th forging cycle, β grain deformed dramatically, and the grain-boundary network developed within the irregular β grain. As the forging cycle increased to 44, the volume fraction of the fine and equiaxial β grain that is less than 20 μm, which is caused by dynamic recrystallization, increased gradually. However, the incomplete dynamic recrystallization region within the original β grain could not be eliminated. As the forging cycle further increased, the volume fraction of the fine and equiaxial β grain did not increase. In contrast, the abnormal grain growth of the β phase occurred during 50th~62nd forging cycle. Here, we attribute the formation of the incomplete dynamic recrystallization region and the abnormal grain growth of the β phase to the high deformation rate of the α + β forging. The refining behavior of β grain and the abnormal coursing β grain, which is found during the multi-cycle multi-axial forging of large-scale Ti-5553 alloy billet, are seldom reported in the isothermal compression of small-scale Ti-5553 alloy specimen. The findings of the paper are instructive for improving the sub-transus forging strategy that is used to fabricate the large-scale homogeneity Ti-5553 alloy billet with fine and equiaxial β grain.
Microstructures and Properties of NbC-Reinforced Ni-Based Coatings Synthesized In Situ by Ultrasonic Vibration-Assisted Laser Cladding
Authors: Lian Guofu , Yue Kun , Zeng Jiayi , Feng Meiyan , Lan Ruqing , Kong Linghua
Published: February 2023

This paper aims to explore the mechanism of an ultrasonic applied field on the microstructures and properties of coatings, and clarify the evolution of the molten pool under different ultrasonic frequencies. The Taguchi experimental design method was adopted in this paper. NbC-reinforced Ni-based coatings were in situ synthesized by laser cladding to investigate the effects of ultrasonic vibration process parameters on the microstructure, pore area, microhardness, and wear resistance of the cladding layer. The results show that the pore area decreases first and then increases as ultrasonic power increases from 600 to 900 W and ultrasonic frequency from 23 to 40 kHz. On the contrary, the hardness and wear resistance increase at first and then decrease. The pore area is minimized at 800 W ultrasonic power and 32 kHz ultrasonic frequency, and the hardness is maximized at 600 W ultrasonic power and 40 kHz ultrasonic frequency. Meanwhile, the highest wear resistance can be obtained when ultrasonic power is 700 W and ultrasonic frequency is 32 kHz. Based on the phase structure analysis, the cladding layer mainly consists of FeNi3, NbC, B4C, and CrB2. Ultrasonic vibration will not change the phase composition of the layer. Combined with the varying G/R value and cooling rate, the reasons for the change in grain morphology in different areas were analyzed to reveal the evolution mechanism of the molten pool under the influence of ultrasound.
Phase Equilibria of the Fe–Cr–Er Ternary System in the Range 973–1273 K
Authors: Li Chenbo , Nie Yusong , Yin Rong , Yang Jifeng , Ye Lideng , Liu Libin , Zhang Ligang
Published: February 2023

Phase relations of the Fe–Cr–Er system in the temperature range 973–1273 K were experimentally investigated using equilibrated alloys. The isothermal sections consisted of 9 single-phase regions, 16 two-phase regions, and 8 three-phase regions at 973 K and 1073 K. At 1273 K, the σ phase disappeared, and liquid appeared. All single phases had a solid solubility range that showed a downward trend with a decrease in temperature. The homogeneity range of the ErFe12−xCrx ternary compound was determined to be x = 1.8–4.5. The more accurate phase relations obtained in this work can better guide the preparation of Fe–Cr–Er alloys in actual production.
Enhanced Properties of Tailored Alumina–Magnesia-Based Dry Ramming Mixes by Calcium Magnesium Aluminate (CMA)
Authors: Tang Hu , Jia Zhenggang , Li Bing , Chen Huazhong , Yuan Wenjie
Published: February 2023

To achieve the goal of “dual-carbon”, induction furnaces with high efficiency and energy-saving advantages are paid more attention in the foundry and metallurgy industries. The service life and safety of induction furnaces strongly depended on the lining because expansion and forward sintering could result in the erosion and slag resistance of the lining. Focusing on the tailoring properties of alumina–magnesia-based dry ramming mixes, calcined magnesia particles were replaced with the novel multi-component materials of calcium magnesium aluminate (CaO-MgO-Al2O3, CMA) with a size of 200 mesh. Properties such as the bulk density, apparent porosity, strength, and slag corrosion resistance of alumina–magnesia-based dry ramming mix containing CMA were evaluated contrastively. The results demonstrate that the penetration index of manganese-bearing slag in dry ramming mixes first decreased and then slightly increased with the addition of CMA. Meanwhile, the permanent linear change in dry ramming mixes was gradually reduced. When the addition of CMA reached 4 wt%, the strength of the dry ramming mixes was slightly greater than the reference, and the slag penetration index was just 75% of the latter.
The Effect of Adding V and Nb Microalloy Elements on the Bake Hardening Properties of ULC Steel before and after Annealing
Authors: Ghanaei Afshin , Edris Hossein , Monajati Hossein , Hamawandi Bejan
Published: February 2023

Bake hardening (BH) is a vital part of special steel production. Studies in this field have focused on steels under homogeneous yielding, but until now, none have been conducted on the phenomena that occur for steels under heterogeneous yielding. In the current study, the effect of adding Nb and V alloying elements on the strength of ultra-low carbon (ULC) steel after bake hardening was investigated. The effects of pre-strain, grain size, and recrystallization annealing temperature were analyzed, as well as the effect of Nb and V on the yield stress caused by the bake hardening process. For this purpose, five types of alloys with different V and Nb contents were melted, cast in an induction furnace, and subjected to hot hammering and hot rolling. Then, cold rolling was applied to the samples by ~80%. To eliminate the effects of cold working, tensile samples were subjected to recrystallization annealing at 750 and 800 °C for 30 min, and the samples were quickly quenched in a mixture of a NaCl solution and ice. The annealed samples were subjected to a pre-tensile strain in the range of 2–12% and then aged in a silicone oil bath at 180 °C for 30 min. Then they were subjected to a tensile test. The obtained results showed that with the increase of the pre-strain and the annealing temperature, the values of baking hardness increased. The presence of V in the composition of steel reduced the annealing temperature.
Evaluation of a Hybrid Underwater Sound-Absorbing Metastructure by Using the Transfer Matrix Method
Authors: Lin Han-Chun , Lu Shu-Cheng , Huang Hsin-Haou
Published: February 2023

In this study, we designed a novel hybrid underwater sound-absorbing material of the metastructure that contains a viscoelastic substrate with a microperforated panel. Two types of sound-absorbing metastructures were combined to achieve satisfactory sound absorption performance in the low-frequency range. A homogenized equivalent layer and the integrated transfer matrix method were used to theoretically evaluate the sound absorption performance of the designed nonhomogeneous hybrid metastructure. The theoretical results were then compared with the results obtained using the finite-element method. The designed hybrid sound-absorbing metastructure exhibited two absorption peaks because of its different sound-absorbing mechanisms. The acoustic performance of the developed metastructure is considerably better than that of a traditional sound absorber, and the sound absorption coefficient of the developed metastructure is 0.8 in the frequency range of 3–10 kHz. In addition, an adjustment method for the practical underwater application of the designed metastructure is described in this research. Further studies show that the sound absorption coefficient of the adjusted metastructure still has 0.75 in the frequency range of 3–10 kHz, which indicates that this metastructure has the potential to be used as an underwater sound-absorbing structure. The results of this study can be used as a reference in the design of other novel hybrid underwater sound-absorbing structures.
Grinding Force and Surface Formation Mechanisms of 17CrNi2MoVNb Alloy When Grinding with CBN and Alumina Wheels
Authors: Jiang Xiaoyang , Liu Ke , Si Mingda , Li Maojun , Gong Pan
Published: February 2023

The 17CrNi2MoVNb alloy is widely used for manufacturing heavy-duty gears in vehicles’ transmission systems, where grinding is a significant process affecting gears’ working performance and service life. This work comprehensively analyzed the grinding force, surface morphology, and surface roughness when grinding 17CrNi2MoVNb alloy using alumina and CBN grinding wheels. Results showed that the maximum normal grinding force from the CBN wheel was only ~67% of the one from the alumina wheel. Due to the small size and limited cutting depth of CBN grains, the grinding force increased by about 20% when the grinding depth increased from 0.02 to 0.03 mm for CBN grinding wheels. Surface defects, including cavities and material tearing, were mainly found on the ground surface when using an alumina grinding wheel. The surface roughness Ra recorded from the CBN grinding wheel mainly ranged from 0.263 to 0.410 μm, accounting for less than 40% of the one from the alumina grinding wheel. The information from this work could provide benchmark data and references for optimizing grinding tools and parameters when manufacturing gears in the vehicle industry.
Expanded Glass for Thermal and Acoustic Insulation from Recycled Post-Consumer Glass and Textile Industry Process Waste
Authors: Cozzarini Luca , De Lorenzi Lorenzo , Barago Nicolò , Sbaizero Orfeo , Bevilacqua Paolo
Published: February 2023

The production of glass foams obtained by recycling post-consumer glass and textile industry processing waste is presented. The mechanical, thermal and acoustic properties were characterized as a function of process temperature and time. The results showed that it is possible to produce glass foams with thermal and acoustic insulation properties from a mixture consisting of 96.5% of glass waste, 1% of textile waste and 2.5% of manganese dioxide, processed at temperatures between 800 and 900 °C for a time between 30 and 90 min. The samples had density in the range of 200–300 kg m−3, porosity of 87–92%, thermal conductivity of 85–105 mW m−1 K−1, noise-reducing factors of 0.15–0.40 and compressive strength of 1.2–3.0 MPa. Although their insulation performance was not as outstanding as that of polymer foams, these materials can emerge as competitive candidates for applications requiring non-flammability and high-temperature load bearing capacity in combination with low weight, mechanical strength, and thermal and acoustic insulation properties. The use of secondary raw materials (which accounted for 97.5% by weight of the synthetic blend) limits the energy required compared to that needed for the extraction, transportation and processing of primary raw materials, making these foams attractive also in terms of environmental footprint.
Sustainable Packaging Design for Molded Expanded Polystyrene Cushion
Authors: Kassim Normah , Rahim Shayfull Zamree Abd , Ibrahim Wan Abd Rahman Assyahid Wan , Shuaib Norshah Afizi , Rahim Irfan Abd , Karim Norizah Abd , Sandu Andrei Victor , Pop Maria , Titu Aurel Mihail , Błoch Katarzyna , Nabiałek Marcin
Published: February 2023

A molded expanded polystyrene (EPS) cushion is a flexible, closed-cell foam that can be molded to fit any packing application and is effective at absorbing shock. However, the packaging waste of EPS cushions causes pollution to landfills and the environment. Despite being known to cause pollution, this sustainable packaging actually has the potential to reduce this environmental pollution because of its reusability. Therefore, the objective of this study is to identify the accurate design parameter that can be emphasized in producing a sustainable design of EPS cushion packaging. An experimental method of drop testing and design simulation analysis was conducted. The effectiveness of the design parameters was also verified. Based on the results, there are four main elements that necessitate careful consideration: rib positioning, EPS cushion thickness, package layout, and packing size. These parameter findings make a significant contribution to sustainable design, where these elements were integrated directly to reduce and reuse packaging material. Thus, it has been concluded that 48 percent of the development cost of the cushion was decreased, 25 percent of mold modification time was significantly saved, and 27 percent of carbon dioxide (CO2) reduction was identified. The findings also aided in the development of productive packaging design, in which these design elements were beneficial to reduce environmental impact. These findings had a significant impact on the manufacturing industry in terms of the economics and time of the molded expanded polystyrene packaging development.
Potential of New Sustainable Green Geopolymer Metal Composite (GGMC) Material as Mould Insert for Rapid Tooling (RT) in Injection Moulding Process
Authors: Yin Allice Tan Mun , Rahim Shayfull Zamree Abd , Al Bakri Abdullah Mohd Mustafa , Nabialek Marcin , Abdellah Abdellah El-hadj , Rennie Allan , Tahir Muhammad Faheem Mohd , Titu Aurel Mihail
Published: February 2023

The investigation of mould inserts in the injection moulding process using metal epoxy composite (MEC) with pure metal filler particles is gaining popularity among researchers. Therefore, to attain zero emissions, the idea of recycling metal waste from industries and workshops must be investigated (waste free) because metal recycling conserves natural resources while requiring less energy to manufacture new products than virgin raw materials would. The utilisation of metal scrap for rapid tooling (RT) in the injection moulding industry is a fascinating and potentially viable approach. On the other hand, epoxy that can endure high temperatures (>220 °C) is challenging to find and expensive. Meanwhile, industrial scrap from coal-fired power plants can be a precursor to creating geopolymer materials with desired physical and mechanical qualities for RT applications. One intriguing attribute of geopolymer is its ability to endure temperatures up to 1000 °C. Nonetheless, geopolymer has a higher compressive strength of 60–80 MPa (8700–11,600 psi) than epoxy (68.95 MPa) (10,000 psi). Aside from its low cost, geopolymer offers superior resilience to harsh environments and high compressive and flexural strength. This research aims to investigate the possibility of generating a new sustainable material by integrating several types of metals in green geopolymer metal composite (GGMC) mould inserts for RT in the injection moulding process. It is necessary to examine and investigate the optimal formulation of GGMC as mould inserts for RT in the injection moulding process. With less expensive and more ecologically friendly components, the GGMC is expected to be a superior choice as a mould insert for RT. This research substantially impacts environmental preservation, cost reduction, and maintaining and sustaining the metal waste management system. As a result of the lower cost of recycled metals, sectors such as mould-making and machining will profit the most.
Strong and Flexible Braiding Pattern of Carbon Nanotubes for Composites: Stiff and Robust Structure Active in Composite Materials
Authors: Ogawa Fumio , Liu Fan , Hashida Toshiyuki
Published: February 2023

Carbon nanotubes (CNTs) exhibit high strength, Young’s modulus, and flexibility and serve as an ideal reinforcement for composite materials. Owing to their toughness against bending and/or twisting, they are typically used as fabric composites. The conventional multiaxial braiding method lacks tension and resultant strength in the thickness direction. Some braiding patterns are proposed; however, they may have shortcomings in flexibility. Thus, this study proposed three types of braiding pattern for fabrics based on natural products such as spider net and honeycomb, in accordance with thickness-direction strength. The spider-net-based structure included wefts with spaces in the center with overlapping warps. At both sides, the warps crossed and contacted the wefts to impart solidness to the structure and enhance its strength as well as flexural stability. In addition, box-type wefts were proposed by unifying the weft and warps into boxes, which enhanced the stability and flexibility of the framework. Finally, we proposed a structure based on rectangular and hexagonal shapes mimicking the honeycomb. Moreover, finite element calculations were performed to investigate the mechanisms through which the proposed structures garnered strength and deformation ability. The average stress in fabrics becomes smaller than half (43%) when four edges are restrained and sliding is inserted. Under three-dimensional forces, our proposed structures underwent mechanisms of wrapping, warping, sliding and doubling, and partial locking to demonstrate their enhanced mechanical properties. Furthermore, we proposed a hierarchical structure specialized for CNTs, which could facilitate applications in structural components of satellites, wind turbines, and ships. The hierarchical structure utilizing discontinuity and sliding benefits the usage for practical mechanical systems.
Changes in Abrasion Resistance of Cast Cr-Ni Steel as a Result of the Formation of Niobium Carbides in Alloy Matrix
Authors: Tęcza Grzegorz
Published: February 2023

Cast austenitic chromium-nickel steel is commonly used for the manufacture of machine parts and components, which are exposed to the attack of corrosive media and abrasive wear during operation. The most commonly used grades include GX2CrNi18-9 and X10CrNi18-8 as well as GX2CrNiMo17-12-2 and X6CrNiMoNb17-12-2. To improve the abrasion resistance of cast chromium-nickel steel, primary niobium carbides were produced in the metallurgical process by increasing the carbon content and adding Fe-Nb. The microstructure of the obtained test castings consisted of an austenitic matrix and primary niobium carbides evenly distributed in this matrix. The measured hardness of the samples after heat treatment ranged from 215 to 240 HV and was higher by about 60 units than the hardness of the reference cast GX10CrNi18-9 steel, which had a hardness of about 180 HV. Compared to the reference cast steel, the abrasive wear resistance of the tested cast chromium-nickel steel (measured in Miller test) with contents of 4.4 and 5.4 wt% Nb increased only slightly, i.e., by 5% for the lower niobium content and 11% for the higher niobium content. Compared to ordinary cast GX10CrNi18-9 steel, the addition of 9.2 wt% Nb reduced the abrasive wear by almost 2.5 times.
Influence of the Hydrogen Doping Method on the Atomic Structure, Mechanical Properties and Relaxation Behaviors of Metallic Glasses
Authors: Zhang Jiacheng , Gao Pengfei , Zhang Weixu
Published: February 2023

The interaction of metallic glasses (MGs) with hydrogen can trigger many interesting physical, chemical and mechanical phenomena. However, atomic-scale understanding is still lacking. In this work, molecular dynamics (MD) simulations are employed to study the atomic structure, mechanical properties and relaxation behaviors of H-doped Ni50Al50 MGs doped by two methods. The properties of H-doped MGs are determined not only by the hydrogen content but also by the doping method. When H atoms are doped into the molten state of samples, H atoms can fully diffuse and interact with metallic atoms, resulting in loose local atomic structures, homogeneous deformation and enhanced β relaxation. In contrast, when H atoms are doped into as-cast MGs, the H content is crucial in affecting the atomic structure and mechanical properties. A small number of H atoms has little influence on the elastic matrix, while the percolation of shear transformation zones (STZs) is hindered by H atoms, resulting in the delay of shear band (SB) formation and an insignificant change in the strength. However, a large number of H atoms can make the elastic matrix loose, leading to the decrease in strength and the transition of the deformation mode from SB to homogeneous deformation. The H effects on the elastic matrix and flow units are also applied to the dynamic relaxation. The deformability of H-doped Ni50Al50 MGs is enhanced by both H-doping methods; however, our results reveal that the mechanisms are different.
Preparation of Micro-Size Spherical Silver Particles and Their Application in Conductive Silver Paste
Authors: Li Na , Li Jun , Wan Xiaoxi , Niu Yifan , Gu Yongwan , Chen Guo , Ju Shaohua
Published: February 2023

In this paper, micro-size spherical silver particles were prepared by using a wet-chemical reduction method. The silver particles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and a laser particle-size analyzer. The results indicate that different types and the content of surfactants can be used to prevent the accumulation, and control the morphology and particle size distribution, of silver particles. Moreover, the morphology of silver particles was changed from polyhedral to spherical when the pH was raised from 1 to 3. Under the optimal synthesis conditions (0.1 mol/L silver nitrate, 0.06 mol/L ascorbic acid, gelatin (5% by weight of silver nitrate), pH = 1), the micro-size spherical silver particles with diameter of 5–8 μm were obtained. In addition, the resistivity of conductive silver paste that prepared with the as-synthesized spherical silver particles was discussed in detail and the average resistivity of the conductive silver paste was 3.57 × 10−5 Ω·cm after sintering at 140 °C for 30 min.
GaAs Nanowire Photodetectors Based on Au Nanoparticles Modification
Authors: Lin Fengyuan , Cui Jinzhi , Zhang Zhihong , Wei Zhipeng , Hou Xiaobing , Meng Bingheng , Liu Yanjun , Tang Jilong , Li Kexue , Liao Lei , Hao Qun
Published: February 2023

A high-performance GaAs nanowire photodetector was fabricated based on the modification of Au nanoparticles (NPs). Au nanoparticles prepared by thermal evaporation were used to modify the defects on the surface of GaAs nanowires. Plasmons and Schottky barriers were also introduced on the surface of the GaAs nanowires, to enhance their light absorption and promote the separation of carriers inside the GaAs nanowires. The research results show that under the appropriate modification time, the dark current of GaAs nanowire photodetectors was reduced. In addition, photocurrent photodetectors increased from 2.39 × 10−10 A to 1.26 × 10−9 A. The responsivity of GaAs nanowire photodetectors correspondingly increased from 0.569 A∙W−1 to 3.047 A∙W−1. The reasons for the improvement of the photodetectors’ performance after modification were analyzed through the energy band theory model. This work proposes a new method to improve the performance of GaAs nanowire photodetectors.
Spin Reorientation Transition and Negative Magnetoresistance in Ferromagnetic NdCrSb3 Single Crystals
Authors: Chen Lei , Zhao Weiyao , Wang Zhaocai , Tang Fang , Fang Yong , Zeng Zhuo , Xia Zhengcai , Cheng Zhenxiang , Cortie David L. , Rule Kirrily C. , Wang Xiaolin , Zheng Renkui
Published: February 2023

High-quality NdCrSb3 single crystals are grown using a Sn-flux method, for electronic transport and magnetic structure study. Ferromagnetic ordering of the Nd3+ and Cr3+ magnetic sublattices are observed at different temperatures and along different crystallographic axes. Due to the Dzyaloshinskii–Moriya interaction between the two magnetic sublattices, the Cr moments rotate from the b axis to the a axis upon cooling, resulting in a spin reorientation (SR) transition. The SR transition is reflected by the temperature-dependent magnetization curves, e.g., the Cr moments rotate from the b axis to the a axis with cooling from 20 to 9 K, leading to a decrease in the b-axis magnetization f and an increase in the a-axis magnetization. Our elastic neutron scattering along the a axis shows decreasing intensity of magnetic (300) peak upon cooling from 20 K, supporting the SR transition. Although the magnetization of two magnetic sublattices favours different crystallographic axes and shows significant anisotropy in magnetic and transport behaviours, their moments are all aligned to the field direction at sufficiently large fields (30 T). Moreover, the magnetic structure within the SR transition region is relatively fragile, which results in negative magnetoresistance by applying magnetic fields along either a or b axis. The metallic NdCrSb3 single crystal with two ferromagnetic sublattices is an ideal system to study the magnetic interactions, as well as their influences on the electronic transport properties.
The Influence of Titanium Oxide Nanoparticles and UV Radiation on the Electrical Properties of PEDOT:PSS-Coated Cotton Fabrics
Authors: Alhashmi Alamer Fahad , Beyari Rawan F.
Published: February 2023

With the rapid growth of electronic textiles, there is a need for highly conductive fabrics containing fewer conductive materials, allowing them to maintain flexibility, low cost and light weight. Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS), is one of the most promising conductive materials for the production of conductive fabrics due to its excellent properties such as solubility, relatively high conductivity, and market availability. Moreover, its electrical conductivity can be enhanced by polar solvents or acid treatment. The aim of this work was to fabricate conductive cotton fabrics with a small fixed amount of PEDOT:PSS and to investigate how titanium dioxide (TiO2) nanoparticles affect the electrical, thermal and structural properties of PEDOT:PSS-coated cotton fabrics. The change in electrical conductivity of the nanocomposite fabric was then related to morphological analysis by scanning electron microscopy and X-ray diffraction. We found that the sheet resistance of the nanocomposite cotton fabric depends on the TiO2 concentration, with a minimum value of 2.68 Ω/□ at 2.92 wt% TiO2. The effect of UV light on the sheet resistance of the nanocomposite cotton fabric was also investigated; we found that UV irradiation leads to an increase in conductivity at an irradiation time of 10 min, after which the conductivity decreases with increasing irradiation time. In addition, the electrical behavior of the nanocomposite cotton fabric as a function of temperature was investigated. The nanocomposite fabrics exhibited metallic behavior at high-TiO2 concentrations of 40.20 wt% and metallic semiconducting behavior at low and medium concentrations of 11.33 and 28.50 wt%, respectively. Interestingly, cotton fabrics coated with nanocomposite possessed excellent washing durability even after seven steam washes.
Electrochemical Impedance Spectroscopy (EIS) Explanation of Single Crystal Cu(100)/Cu(111) in Different Corrosion Stages
Authors: Lin Qihao , Chen Guoqing , Zou Shiwen , Zhou Wenlong , Fu Xuesong , Shi Shuyan
Published: February 2023

Copper and its alloys are used widely in marine environments, and anisotropic corrosion influences the corrosion kinetics of copper. Corrosion of copper in an electrolyte containing Cl− is described as a dissolution–deposition process, which is a prolonged process. Therefore, it is laborious to clarify the corrosion anisotropy in different stages. In this paper, electrochemical impedance spectroscopy (EIS) following elapsed open circuit potential (OCP) test with 0 h (0H), 24 h (24H) and 10 days (10D) was adopted. To exclude interruptions such as grain boundary and neighbor effect, single crystal (SC) Cu(100) and Cu(111) were employed. After 10D OCP, cross-sectional slices were cut and picked up by a focused ion beam (FIB). The results showed that the deposited oxide was Cu2O and Cu(100)/Cu(111) experienced different corrosion behaviors. In general, Cu(100) showed more excellent corrosion resistance. Combined with equivalent electrical circuit (EEC) diagrams, the corrosion mechanism of Cu(100)/Cu(111) in different stages was proposed. In the initial stage, a smaller capacitive loop of Cu(111) suggested preferential adsorption of Cl− on air-formed oxide film on Cu(111). Deposited oxide and exposed bare metals also played an important role in corrosion resistance. Rectangle indentations and pyramidal structures formed on Cu(100)/Cu(111), respectively. Finally, a perfect interface on Cu(100) explained the tremendous capacitive loop and higher impedance (14,274 Ω·cm2). Moreover, defects in the oxides on Cu(111) provided channels for the penetration of electrolyte, leading to a lower impedance (9423 Ω·cm2) after 10D corrosion.
Significance of Melt Pool Structure on the Hydrogen Embrittlement Behavior of a Selective Laser-Melted 316L Austenitic Stainless Steel
Authors: Liu Jie , Yang Huajie , Meng Lingxiao , Liu Di , Xu Tianqi , Xu Daokui , Shao Xiaohong , Shao Chenwei , Li Shujun , Zhang Peng , Zhang Zhefeng
Published: February 2023

The hydrogen embrittlement (HE) behavior of a selective laser-melted (SLM) 316L austenitic stainless steel has been investigated by hydrogen charging experiments and slow strain rate tensile tests (SSRTs) at room temperature. The results revealed that compared to the samples without H, the ultimate tensile strength (UTS) and elongation (EL) of specimens were decreased from 572 MPa to 552 MPa and from 60% to 36%, respectively, after 4 h of electrochemical hydrogenation with a current density of 100 mA/cm2. The negative effects of hydrogen charging were more pronounced on the samples’ ductility than on their strength. A quasi in situ EBSD observation proved that there was little phase transformation in the samples but an increased density of low angle grain boundaries, after 4 h H charging. After strain was applied, the surface of the H-sample displayed many hydrogen-induced cracks along the melt pool boundaries (MPBs) showing that these MPBs were the preferred areas for the gathering and transferring of hydrogen.
Research Regarding the Development of the Combustion Chamber of Internal Combustion Engines with Opposite Pistons
Authors: Beles Horia , Tusinean Adrian , Mitran Tudor , Scurt Florin Bogdan
Published: February 2023

The reduction in environment pollutant emissions is one of the main challenges regarding ground transportation. Internal combustion engines, used especially in hybrid propulsion systems, may be a solution in the transition to fully electric cars. Therefore, more efficient engines in terms of fuel consumption, emission generation and power density must be developed. This paper presents research regarding the architecture of the combustion chamber of an internal combustion engine with opposed pistons. The aim of this research was to find a combustion chamber architecture that would enable the engine to perform close to the program target of: NOx < 3.5 g/kWh, smoke (FSN) < 1, specific fuel consumption (bsfc) < 198 g/kWh. Three variants of the combustion chamber’s architecture have been studied. After the experimental research, the conclusion was that none of them fully reached the target; however, significant improvements have been achieved compared with the starting point. As a result, further research needs to be carried out in order to reach and even exceed the target.
Gear Crack Detection Based on Vibration Analysis Techniques and Statistical Process Control Charts (SPCC)
Authors: Jorani Rasheed Majeed , Haddar Maroua , Chaari Fakher , Haddar Mohamed
Published: February 2023

Vibration condition monitoring is a non-devastating technique that can be performed to detect tooth cracks propagating in gear systems. This paper proposes to apply a new methodology using time-domain analysis, frequency-domain analysis, and statistical process control charts (SPCC) for gear crack detection of a 10 DOF dynamic model of spiral bevel gear system (SBGS). The gear mesh stiffness effect used in the model has been studied analytically for different levels of crack faults. Adding Gaussian white noise is discussed as the first step to simulating the initial modeling signals of real-world conditions. Second, time-domain signal analysis was performed to identify periodic vibration pulses as failure components and calculate the statistical standard deviation (STD) feature as a fault-sensitive feature. Third, a fast Fourier transform (FFT) to time signals of the variable gear mesh stiffness was applied to determine the gear mesh frequency and sidebands to detect tooth cracks. Fourth, the SPCC was designed using the Shewhart X-bar chart and an exponentially weighted moving average (EWMA) chart based on the STD feature of the healthy gears. Finally, in the testing stage, the control charts are carried out with simulation signals under faulty conditions to detect the different levels of cracks. The results showed that the EWMA chart outperformed the time domain analysis, frequency domain analysis, and Shewhart X-bar chart in detecting all levels of cracks at an early stage.
Research and Analysis of the Characteristics of the Brushless Doubly-Fed Machine with High-Performance Decoupling Control
Authors: Xia Chaoying , Wang Nannan
Published: February 2023

The paper presents the state-space (SS) model of the brushless double-fed machine (BDFM) by taking the negative conjugate (NC) transformation of the power machine’s correlation variable when the current source of the control machine is supplied in the m-t reference frame. Based on this, the testing method of machine parameters is given, and the SS model described by five parameters is obtained. The derivation process and realization method of the slip-frequency vector feedback linearization control (SFV-FLC) strategy are given. Then, researching the SS equation in the m-t reference frame by the control machine rotor field-oriented, the relationship between the maximum and minimum output torque and the control machine rotor flux amplitude and slip velocity, the machine parameters are given considering power supply constraints. Finally, the validity of the theoretical analysis is verified by simulation and experiment, and the feasibility of the decoupling control method are also demonstrated.
The Use of Diffusion Weighted Imaging and Intravoxel Incoherent Motion to Assess Edema and Perfusion in Abdominal Organs during Endotoxemia
Authors: Marchesi Silvia , Lundström Elin , Ahlström Håkan , Lipcsey Miklós
Published: February 2023

Diffusion weighted magnetic resonance imaging (DW-MRI) technique probing the microscopic movement of water molecules in tissue, allows for the quantification of water diffusivity and the contribution of perfusion to the total amount of water. In the last decades, its use in organs other than the brain has increased and it has successfully been applied to abdominal organs; otherwise the use of DWI for the assessment of perfusion (by measuring perfusion fraction and edema (by measuring the apparent diffusion coefficient—ADC) of entire organs is not a clinical standard. The aim of this paper is to assess whether DWI, specifically IVIM, can accurately assess edema (the amount of water contained in a tissue) and perfusion in abdominal organs (liver, spleen, intestine and kidneys) in an endotoxemic porcine model. Endotoxemia was induced in 20 piglets and they were divided into three groups: HM group (HighMAP, mean arterial pressure was maintained >65 mmHg by noradrenaline infusion), LM group (LowMAP, MAP was maintained between 50 and 60 mmHg) and LTD (the thoracic duct was ligated to increase abdominal edema). In addition, a fourth group of healthy controls (four animals) underwent MRI. Edema was also assessed by wet–dry weight in liver, spleen and intestine; and perfusion was assessed by hemodynamics, lactate concentration and SvO2. ADC was found to be higher in the intestine of the LTD group compared with the other groups, in accordance with wet–dry weight. In addition, ADC in kidneys was found to be correlated to glomerular filtration rate. f was correlated with hemodynamics in kidneys and liver. The presented data show that there is a potential for clinical use of the technique in septic patients.
Improved Feature Selection Based on Chaos Game Optimization for Social Internet of Things with a Novel Deep Learning Model
Authors: Dahou Abdelghani , Chelloug Samia Allaoua , Alduailij Mai , Elaziz Mohamed Abd
Published: February 2023

The Social Internet of Things (SIoT) ecosystem tends to process and analyze extensive data generated by users from both social networks and Internet of Things (IoT) systems and derives knowledge and diagnoses from all connected objects. To overcome many challenges in the SIoT system, such as big data management, analysis, and reporting, robust algorithms should be proposed and validated. Thus, in this work, we propose a framework to tackle the high dimensionality of transferred data over the SIoT system and improve the performance of several applications with different data types. The proposed framework comprises two parts: Transformer CNN (TransCNN), a deep learning model for feature extraction, and the Chaos Game Optimization (CGO) algorithm for feature selection. To validate the framework’s effectiveness, several datasets with different data types were selected, and various experiments were conducted compared to other methods. The results showed that the efficiency of the developed method is better than other models according to the performance metrics in the SIoT environment. In addition, the average of the developed method based on the accuracy, sensitivity, specificity, number of selected features, and fitness value is 88.30%, 87.20%, 92.94%, 44.375, and 0.1082, respectively. The mean rank obtained using the Friedman test is the best value overall for the competitive algorithms.
Robust Statistic Estimation in Constrained Optimal Control Problems of Pollution Accumulation (Part II: Markovian Switchings)
Authors: Escobedo-Trujillo Beatris Adriana , López-Barrientos José Daniel , Higuera-Chan Carmen Geraldi , Alaffita-Hernández Francisco Alejandro
Published: February 2023

This piece is a follow-up of the research started by the authors on the constrained optimal control problem applied to pollution accumulation. We consider a dynamic system governed by a diffusion process with multiple modes that depends on an unknown parameter. We will study the components of the model and their restrictions and propose a scheme to solve the problem in which it is possible to determine (adaptive) policies that maximize a suitable discounted reward criterion using standard dynamic programming techniques in combination with discrete estimation methods for the unknown parameter. Finally, we develop a numerical example to illustrate our results with a particular case of the method of minimum least square error approximation.
A Dynamic Spatio-Temporal Stochastic Modeling Approach of Emergency Calls in an Urban Context
Authors: Payares-Garcia David , Platero Javier , Mateu Jorge
Published: February 2023

Emergency calls are defined by an ever-expanding utilisation of information and sensing technology, leading to extensive volumes of spatio-temporal high-resolution data. The spatial and temporal character of the emergency calls is leveraged by authorities to allocate resources and infrastructure for an effective response, to identify high-risk event areas, and to develop contingency strategies. In this context, the spatio-temporal analysis of emergency calls is crucial to understanding and mitigating distress situations. However, modelling and predicting crime-related emergency calls remain challenging due to their heterogeneous and dynamic nature with complex underlying processes. In this context, we propose a modelling strategy that accounts for the intrinsic complex space–time dynamics of some crime data on cities by handling complex advection, diffusion, relocation, and volatility processes. This study presents a predictive framework capable of assimilating data and providing confidence estimates on the predictions. By analysing the dynamics of the weekly number of emergency calls in Valencia, Spain, for ten years (2010–2020), we aim to understand and forecast the spatio-temporal behaviour of emergency calls in an urban environment. We include putative geographical variables, as well as distances to relevant city landmarks, into the spatio-temporal point process modelling framework to measure the effect deterministic components exert on the intensity of emergency calls in Valencia. Our results show how landmarks attract or repel offenders and act as proxies to identify areas with high or low emergency calls. We are also able to estimate the weekly average growth and decay in space and time of the emergency calls. Our proposal is intended to guide mitigation strategies and policy.
Comparing Friends and Peer Tutors Amidst COVID-19 Using Social Network Analysis
Authors: Rahim Nurul Zahirah Abd , Bahari Nurun Najwa , Azzimi Nur Syaza Mohd , Zamzuri Zamira Hasanah , Bahaludin Hafizah , Mohammad Nurul Farahain , Razak Fatimah Abdul
Published: February 2023

COVID-19 has drastically changed the teaching patterns of higher education from face-to-face to online learning, and it has also affected students’ engagement socially and academically. Understanding the nature of students’ engagement during online learning can help in identifying related issues so that various initiatives can be implemented in adapting to this situation. In this study, social network analysis is conducted to gain insights on students’ engagement during COVID-19. Directed and weighted networks were used to visualize and analyze friendship as well as peer tutor networks obtained from online questionnaires answered by all students in the class. Contrasting friends and peer tutors reveals some hidden interactions between students and shines some light on dynamics of the online learning community. The results indicate that, popular and important peer tutors may not be high achievers and thus possibly contributing to the spread of misinformation in the online learning community. By comparing weighted indegree and betweenness centrality values, we suggest approaches to cultivate a healthy online learning community. This study highlights the use of social network analysis to assist and monitor students’ engagement and further formulate strategies in order to make the class a conducive online learning community, particularly in the advent of online learning in higher education institutions.