bluuebunny/crossref_metadata_2025 huggingface dataset:
Low Temperature Transient Liquid Phase Bonding of Alumina Ceramics with the Bi2O3-ZnO Interlayer
Authors: Stosz Maria , Narayanasamy Sathya , Graule Thomas , Kata Dariusz , Blugan Gurdial
Published: October 2022

Alumina ceramics were joined by a transient liquid phase (TLP) bonding method at relatively lower temperatures, using mixed powders of Bi2O3 and ZnO with different weight ratios as interlayers between the ceramic components. Bonding was achieved at 750 °C for several of the prepared interlayer mixtures, which makes the applied approach attractive due to the relatively lower joining temperature and potentially low fabrication costs. Measurements by SEM and EDX were used to study the microstructure and chemical analysis of the obtained joints. It also allowed us to investigate the diffusion mechanism occurring in the systems, which resulted in the hypothesis that Zn2+/ZnO diffuses through the ceramics. XRD and Raman spectra were acquired to examine the reaction products that formed during the thermal treatment. The results showed that both ZnO and Bi2O3 react with each other as well as with alumina to form spinel and other products.
Evaluation of Laminated Composite Beam Theory Accuracy
Authors: Lyu Yu-Ting , Hung Tsung-Pin , Ay Her-Chang , Tsai Hsiu-An , Chiang Yih-Cherng
Published: October 2022

Carbon fiber-reinforced polymer (CFRP) has been widely implemented in electric vehicle bodies and aircraft fuselage structures. The purpose of CFRP is to reduce the weight and impart rigidity in the final product. A beam structure is typically used to bear the structural load, and the rigidity of the beam can be changed by arranging the laminated fibers at different angles. In this study, a composite I-beam is used as an example in engineering components. Because the theoretical model of the superimposed composite I-beam is established, the theoretical formula is based on the theoretical assumptions of the two-dimensional composite beam, and is combined with the traditional composite plate theory to analyze the maximum bending stress, strain, and deflection. During the theoretical derivation, it is assumed that the flanges of the I-beams are divided into narrow and wide flanges. The beams are considered as structures of beams and flatbeds. When a narrow flange is loaded in the side, the wide flange has no lateral deformation, and the lateral moments are neglected. Therefore, the accuracy of this formula needs to be verified. The purpose of this study is to verify the accuracy of theoretical solutions for the deflection and stress analysis of composite beams. A finite element analysis model is used as the basis for comparing the theoretical solutions. The results indicate that when the aspect ratio of the beam is >15, the theoretical solution will have better accuracy. Without the addition of the material, when 0° ply is placed on the outermost layer of the flange of the nonsymmetric beam, the effective rigidity of the beam is increased by 4–5% compared with the symmetrical beam. The accuracy range of the theoretical solution for the composite beams can be accurately defined based on the results of this study.
Characterization of the Nano-Rod Arrays of Pyrite Thin Films Prepared by Aqueous Chemical Growth and a Subsequent Sulfurization
Authors: Talaeizadeh Mohammad , Seyyed Ebrahimi Seyyed Ali , Khosravi Payam , Hamawandi Bejan
Published: October 2022

Pyrite is an earth-abundant and low-cost material with a specific collection of properties including a low band gap and high absorption coefficient of solar light. These properties make pyrite a good choice in a wide variety of applications such as catalysts, batteries, and photovoltaic devices. A thin film composed of vertically aligned pyrite nano-rods was processed via a hydration-condensation method followed by subsequent aging and sulfurization. In this process, no ionic salt was used which resulted in a lower cost process with a lower level of impurities. Field emission scanning electron microscopy, X-ray diffraction, and Raman spectroscopy analyses were used to characterize the thin films in different steps of the process. The major impurity of the final thin films was the marcasite phase according to the Raman analysis which could be minimized by lowering sulfurizing time to about 60 min. In addition, after structural, electrical, and optical characterization of thin films, these layers’ performances in a photovoltaic device were also examined. After deposition of a thin aluminum layer, Schottky-type solar cells of pyrite formed which were then illuminated to measure their current-voltage characteristics. The results show that a combination of low-cost materials and a low-cost preparation method is applicable for building future solar cells.
Destabilization and Ion Conductivity of Yttria-Stabilized Zirconia for Solid Oxide Electrolyte by Thermal Aging
Authors: Lee Hwanseok , Jo Kanghee , Park Min-sung , Kim Taewoo , Lee Heesoo
Published: October 2022

The degradation behavior of yttria-stabilized zirconia by thermal aging was investigated in terms of phase transformation, local atomic structure, and electrical conductivity. The average grain size of 8YSZ was increased from 20.83 μm to 25.81 μm with increasing aging temperature. All 8YSZ samples degraded at different temperatures had a predominantly cubic structure. The (400) peak of 8YSZ deteriorated at 1300 and 1400 °C shifted to a high angle, and the peak of tetragonal was not indexed. For 8YSZ degraded at 1500 °C, the (400) peak shifted to a lower angle, and the peak of tetragonal was identified. Analysis of the local microstructure of aged 8YSZ using extended X-ray absorption fine structure showed that the intensity of the Zr-O peak gradually increased and that the intensity of the peak of cationic Zr decreased as the aging temperature increased. The changes in the peaks indicate that the oxygen vacancies were reduced and Y3+ ions escaped from the lattice, leading to the destabilization of 8YSZ. The activation energies of 8YSZ at 1300 °C and 1400 °C were derived to be 0.86 and 0.87 eV, respectively, and the activation energy of 8YSZ at 1500 °C increased significantly to 0.92 eV. With the thermal deterioration of 8YSZ, the cation (Y3+) escaped from the lattice and the number of oxygen vacancies decreased, resulting in the formation of a tetragonal structure and high activation energy at 1500 °C.
Impact of Torrefaction on Fuel Properties of Aspiration Cleaning Residues
Authors: Tamelová Barbora , Malaťák Jan , Velebil Jan , Gendek Arkadiusz , Aniszewska Monika
Published: October 2022

To maximise the use of biomass for energy purposes, there are various options for converting biomass to biofuels through thermochemical conversion processes, one of which is torrefaction. Higher utilisation of waste from the aspiration cleaning of grains, such as wheat or maize, could be one of the means through which the dependence on fossil fuels could be reduced in the spirit of a circular economy. In this study, the effect of torrefaction on fuel properties of agricultural residues was investigated. The tested materials were waste by-products from the aspiration cleaning of maize grains and waste from wheat. The materials were treated by torrefaction under a nitrogen atmosphere (225 °C, 250 °C, and 275 °C), over a residence time of 30 min. During the treatment, weight loss was monitored as a function of time. Proximate and elemental composition, as well as calorific values, were analysed before and after torrefaction. Torrefaction has a positive effect on the properties of the fuels in the samples studied, as shown by the results. The carbon content increased the most between temperatures of 250 °C and 275 °C, i.e., by 11.7% wt. in waste from maize. The oxygen content in the maize waste samples decreased by 38.99% wt. after torrefaction, and in wheat waste, it decreased by 37.20% wt. compared to the original. The net calorific value increased with increasing temperatures of process and reached a value of 23.56 MJ·kg−1 at a peak temperature of 275 °C in by-products from maize. To express the influence of the treatments on combustion behaviour, stoichiometric combustion calculations were performed. Differences of up to 20% in stoichiometric combustion parameters were found between the two types of waste. A similar case was found for fuel consumption, where a difference of 19% was achieved for torrefaction at a temperature of 275 °C, which fundamentally differentiated these fuels.
Effects of Deformation at High, Medium, and Cryogenic Temperatures on the Microstructures and Mechanical Properties of Al-Zn-Mg-Cu Alloys
Authors: Zhang Wenxue , Yi Youping , Huang Shiquan , He Hailin , Dong Fei
Published: October 2022

Thermomechanical treatment is an effective way to refine the coarse microstructures of aluminum alloys. In this work, multiaxial forging deformation at high, medium, and cryogenic temperatures (i.e., 450, 250, and −180 °C, respectively) was performed on 7085 Al-Zn-Mg-Cu alloys, and its effect on the microstructure evolution and mechanical properties during the subsequent T6 heat treatment process was studied. The results revealed that the coarse particles were broken into finer particles when deformed at cryogenic temperatures, promoting the dissolution of the material after solid solution treatment. Dynamic recrystallization occurred when deformed at 450 °C; however, more dislocations and substructures were found in the samples deformed at 250 and −180 °C, causing static recrystallization after solid solution treatment. The cryogenic deformed sample exhibited a more intense and homogeneous precipitation phase distribution. The strength of the sample deformed at high temperature was high, but its elongation was low, while the strength of the sample deformed at medium temperature was low. The microstructure refinement of the cryogenic deformed sample led to high comprehensive mechanical properties, with an ultimate tensile strength of 535 MPa, a yield strength of 506 MPa, and a fracture elongation of 11.1%.
Macrocycle as a “Container” for Dinitramide Salts
Authors: Il’yasov Sergey G. , Glukhacheva Vera S. , Il’yasov Dmitri S. , Zhukov Egor E.
Published: October 2022

Dinitramic acid salts are promising components as oxidizers and burning-rate modifiers of high-energy compositions. However, most of these salts are not free of drawbacks such as hygroscopicity. Therefore, their application under special conditions of use and storage is limited. The synthesis and storage of stable dinitramic acid salts is a topical issue. Here, we synthesized an adduct starting from the nickel salt of dinitramic acid with carbohydrazide and glyoxal to settle the problem of stability and storage of that salt. The chemical composition of the adduct was confirmed by infrared spectroscopy and elemental analysis. The Ni content was determined by atomic emission spectroscopy. Thermogravimetric DSC and TGA analyses showed the adduct to have three decomposition stages. The adduct exhibits a good thermal stability and a low sensitivity to mechanical stimuli. Here, the adduct is demonstrated to be a promising burning-rate inhibitor of pyrotechnic compositions.
Effects of Al-Ti-C Refiner and Forming Processes on the Microstructure and Properties of Al-Zn-Mg-Cu Alloys
Authors: Liao Qiao , Li Jianyu , Liu Jianping , Lü Shulin , Chen Lu , Guo Wei , Wu Shusen
Published: October 2022

In this paper, the refinement effect of Al-5Ti-0.2C refiner on Al-Zn-Mg-Cu alloys was first investigated, and then the effects of three forming processes, i.e., Gravity Casting (GC), Squeeze Casting (SC), and Squeeze Casting after Ultrasonic Treatment (UT-SC), on microstructure and properties of Al-Zn-Mg-Cu alloys were studied. The results show that the refining effect of Al-5Ti-0.2C refiner is obvious; first, the average grain size of the alloy decreases and then increases with the increase in Ti content from 0.15 wt.% to 0.3 wt.%. The optimal amount of added Al-5Ti-0.2C is 0.2 wt.% Ti content. The good refining effect is attributed to the formation of TiC particles and Al3Ti compounds by the refiner, which can all be the nucleus of solidification. The poor refining effect when the Ti content was more than 0.2 wt.% is due to the formation of coarse Al3Ti particles. The results of three forming processes that cast Al-Zn-Mg-Cu alloys under the addition of Al-5Ti-0.2C with 0.2 wt.% Ti content show that the mechanical properties under the UT-SC process are the best; the tensile strength in the as-cast state reaches 367 MPa, and the elongation is 3.84%. The effect of tiny TiC particles in the refiner on the microstructure and properties of Al-Zn-Mg-Cu alloys is also discussed.
Dynamic Response of Sandwich Tubes with Continuously Density-Graded Aluminum Foam Cores under Internal Explosion Load
Authors: Wang Anshuai , Yu Xuehui , Wang Han , Li Yu , Zhang Jie , Fan Xueling
Published: October 2022

In this paper, the dynamic response of continually density-graded aluminum foam sandwich tubes under internal explosion load was studied. A 3D mesoscopic finite-element model of continually density-graded aluminum foam sandwich tubes was established by the 3D-Voronoi technology. The finite-element results were compared with the existing experimental results, and the rationality of the model was verified. The influences of the core density distribution, the core density gradient, and the core thickness on the blast resistance of the sandwich tubes were analyzed. The results showed that the blast resistance of the sandwich tube with the negative-gradient core is better than that of the sandwich tube with the uniform core. While the blast resistance of the sandwich tube with the positive-gradient core or the middle-hard-gradient core is worse than that of the sandwich tube with the uniform core. For the sandwich tube with the negative-gradient core, the core density gradient increased, and the blast resistance decreased. Increasing the thickness of the core can effectively decrease the deformation of the outer tube of the sandwich tube, but the specific energy absorption of both the whole sandwich tube and its core also decreases.
Analysis and Suppression of Thermal Magnetic Noise of Ferrite in the SERF Co-Magnetometer
Authors: Pang Haoying , Liu Feng , Fan Wengfeng , Wu Jiaqi , Yuan Qi , Wu Zhihong , Quan Wei
Published: October 2022

The ferrite magnetic shield is widely used in ultra-high-sensitivity atomic sensors because of its low noise characteristics. However, its noise level varies with temperature and affects the performance of the spin-exchange relaxation-free (SERF) co-magnetometer. Therefore, it is necessary to analyze and suppress the thermal magnetic noise. In this paper, the thermal magnetic noise model of a ferrite magnetic shield is established, and the thermal magnetic noise of ferrite is calculated more accurately by testing the low-frequency complex permeability at different temperatures. A temperature suppression method based on the improved heat dissipation efficiency of the ferrite magnetic shield is also proposed. The magnetic noise of the ferrite is reduced by 46.7%. The experiment is basically consistent with the theory. The sensitivity of the co-magnetometer is decreased significantly, from 1.21 × 10−5°/s/Hz1/2 to 7.02 × 10−6°/s/Hz1/2 at 1 Hz. The experimental results demonstrate the effectiveness of the proposed method. In addition, the study is also helpful for evaluating the thermal magnetic noise of other materials.
Accurate Characterization of the Adhesive Layer Thickness of Ceramic Bonding Structures Using Terahertz Time-Domain Spectroscopy
Authors: Yang Xiuwei , Zhang Dehai , Wu Biyuan , Zhang Kaihua , Yang Bing , Wang Zhongmin , Wu Xiaohu
Published: October 2022

Ceramic adhesive structures have been increasingly used in aerospace applications. However, the peaks of the signal on the upper and lower surface of the adhesive layer are difficult to measure directly due to the thin thickness of the adhesive layer and the effect of the attenuation dispersion of the ceramic layer. Thus, the existing non-destructive testing techniques have been ineffective in detecting adhesive quality. In this paper, the thickness of the adhesive layer is measured using terahertz time-domain spectroscopy. A sparse deconvolution method is proposed for the terahertz time-domain spectral signal of ceramic adhesive structures with different adhesive layer thicknesses. The results show that the methods proposed in this paper can realize the separation of reflection signals for glue layers with a thickness of 0.20 mm. By comparing with a wavelet denoising method and a modified covariance method (AR/MCM), the effectiveness of the sparse deconvolution method in estimating the thickness of the glue layer is demonstrated. This work will provide the theoretical and experimental basis for using terahertz time-domain spectroscopy to detect the homogeneity of ceramic adhesive structures.
Fatigue Tests and Analysis on Welded Joints of Weathering Steel
Authors: Sheng Rongrong , Liu Yuqing , Yang Ying , Hao Rui , Chen Airong
Published: October 2022

To investigate the fatigue performance of vertical web stiffener to deck plate welded joints in weathering steel box girders, six specimens of the weathering steel (WS) Q345qNH, four specimens of WS Q420qNH, and four specimens of the plain carbon steel (CS) Q345q for comparison were tested by a vibratory fatigue testing machine, considering different steel grades, yield strengths, stiffener plate thicknesses, and weld types. The fatigue strength was evaluated based on S-N curves and the crack propagation was analyzed by linear elastic fracture mechanics (LEFM). The results show that the fatigue crack of the welded joints was initiated from the end weld toe of the deck plate and subsequently propagated both along the thickness of the deck plate and in the direction perpendicular to the stiffener plate. The fatigue crack initiation and propagation life of WS Q345qNH specimens were longer than those of CS Q345q specimens. The fatigue crack propagation life of WS Q345qNH specimens was longer than that of WS Q420qNH specimens, while the initiation life bore little relationship to the yield strength. Increasing the stiffener plate thickness effectively delayed crack initiation and slowed down its propagation. Compared with fillet welds, full penetration welds extended the fatigue crack propagation life, while no significant improvement was implied for the initiation life. The WS and CS specimens could be classified as having the same fatigue strengths by nominal stress, hot spot stress, and effective notch stress approaches, which were FAT 50, FAT 100, and FAT 225, respectively. Meanwhile, their material constants for LEFM were relatively close to each other.
Dynamic Polarization Behaviors of Equimolar CoCrFeNi High-Entropy Alloy Compared with 304 Stainless Steel in 0.5 M H2SO4 Aerated Aqueous Solution
Authors: Yen Chao-Chun , Tsai Ting-Lun , Wu Bo-Wei , Lo Yu-Chieh , Tsai Ming-Hung , Yen Shiow-Kang
Published: October 2022

Three corrosion potentials and three corrosion current densities are clearly identified before the passivation for both dynamic polarization curves of equimolar CoCrFeNi high-entropy alloy (HEA) and 304 stainless steel (304SS) in 0.5 M H2SO4 aerated aqueous solution, by decomposing anodic and cathodic polarization curves. The passivated current density of the former is greater than the latter, compliant with not only the constant of solubility product (ksp) and redox equilibrium potential (Eeq) of each metal hydroxide but also the sequence of bond energy (Eb) for monolayer hydroxide on their facets derived from the first principle founded on density function theory. However, the total amount of ion releasing from HEA is less than 304SS, since the hydroxide/oxide film formed in the air of the latter containing greater amounts of Fe(Ⅱ) and Mn(Ⅱ) is less stable around corrosion potentials while they are further oxidized into more stable Fe(Ⅲ) and Mn(ⅢorⅣ) with much lower ksp, leading to the much less increasing ratios of ion releases from 0.25 to 0.6 V.
A New Method for Abrin Detection Based on the Interaction between Target Molecules and Fluorescently Labeled Aptamers on Magnetic Microspheres
Authors: Liu Zhiwei , Tong Zhaoyang , Wu Yuting , Liu Bing , Feng Shasha , Mu Xihui , Wang Jiang , Du Bin , Xu Jianjie , Liu Shuai
Published: October 2022

A quantitative structure–activity relationship (QSAR) model for the structure and affinity of abrin aptamers was established. A higher affinity abrin aptamer based on the established QSAR model was screened by site-directed mutagenesis. The fluorescence quenching effect between magnetic microspheres and fluorescent molecules was studied for the first time. A new method for abrin detection based on the interaction between target molecules and fluorescently labeled aptamers on magnetic microspheres was developed, with the detection limit of 5 ng mL−1. This method can overcome the influence of complex environmental interferents in abrin detection and can meet the analysis requirements for simulated samples such as water, soil, and food.
Green Synthesis of Silver Nanoparticles from Camellia sinensis and Its Antimicrobial and Antibiofilm Effect against Clinical Isolates
Authors: Ali Syed , Jalal Mohammad , Ahmad Hilal , Sharma Diwakar , Ahmad Akil , Umar Khalid , Khan Haris
Published: October 2022

The green synthesis method of was used for the synthesis of silver nanoparticles using Camellia sinensis (green tea). The Camellia sinensis silver nanoparticles (CS-AgNPs) were characterized using different techniques, including UV-Vis (ultra violet-visible), SEM (scanning electron microscopy), TEM (transmission electron microscopy), and XRD (X-ray diffraction). The average size of the CS-AgNPs was 52 nm, according to TEM. The CS-AgNPs showed excellent antibacterial and antifungal activity. The MIC (minimum inhibitory concentration) against bacterial isolates varied from 31.25 to 62.5 µg/mL, whereas for fungal isolates, the MIC varied from 125 to 250 µg/mL. The presence of a zone in the well diffusion assay showed the antimicrobial nature of CS-AgNPs. Further, CLSM (confocal laser scanning microscopy) showed that CS-AgNPs possess antibiofilm activity. The interaction of CS-AgNPs with the Candidal cells was analyzed using TEM, and it was revealed that CS-AgNPs entered the cell and disrupted the cell machinery.
A Bibliometric Analysis of Research Trends in Geopolymer
Authors: Matsimbe Jabulani , Dinka Megersa , Olukanni David , Musonda Innocent
Published: October 2022

Geopolymer is an inorganic material formed through the chemical reaction of an aluminosilicate precursor and an alkaline or acidic activating solution. It is seen as a green new alternative binder to ordinary Portland cement (OPC) for sustainable infrastructure development. The strength of the unary or blended geopolymer product is dependent on the composition and properties of the polymeric gel influenced by the ratios of Al2O3/SiO2, CaO/SiO2, CaO/(SiO2 + Al2O3), Na2SiO3/NaOH, SiO2/Na2O, and liquid/binder (L/B). Essential scientific inquiry has been progressively addressed by utilizing expert assessment and research metrics. The network visualization of bibliometric co-occurrence and co-citations is of particular significance. The present study aims to highlight the trends and progress of the most influential publication sources, keywords, authors, articles, and countries in geopolymer research in the last 10 years. Bibliometric data were retrieved through Scopus and visualized in VOSviewer to create bibliometric networks. The yearly distribution and growth trends (April 2011–2022) of geopolymer, geopolymer mortar, and geopolymer concrete before (after) applying inclusion criteria were from 754 to 9887 (5186), 47 to 1374 (866), and 145 to 3721 (2253), respectively, attributed to the discoveries in more precursor materials such as laterite and the growing interest in fire and heat-resistant structures, water and wastewater treatment, cement and concrete, and brick manufacturing. The top three journals in terms of prestige for geopolymer publications were the Journal of Hazardous Materials with an impact factor equal to 14.224 and h-index equal to 307, Cement and Concrete Research with an impact factor equal to 11.958 and h-index equal to 239, and the Journal of Cleaner Production with an impact factor equal to 11.072 and h-index equal to 232. The top three journals in terms of average citation per document were Cement and Concrete Research (135.75), Materials and Design (75), and Cement and Concrete Composites (68.35). Keywords such as “geopolymers”, “inorganic polymer”, “geopolymer”, “compressive strength”, “fly ash”, and “geopolymer concrete” had the highest occurrences in publications. John Provis—University of Sheffield, Prinya Chindaprasirt—Khon Kaen University, and Jay Sanjayan—Swinburne University of Technology had the highest total citations of 6377, 5626, and 4311, respectively. The highest number of publications were from China, India, Australia, the United States of America, and Malaysia. The bibliometric findings from this study can act as a tool for academicians and policymakers to exchange research expertise, collaborate on novel geopolymer research, and create innovative joint ventures.
Pressure-Induced Tunable Charge Carrier Dynamics in Mn-Doped CsPbBr3 Perovskite
Authors: Du Luchao , Shi Xiaoping , Duan Menghan , Shi Ying
Published: October 2022

All-inorganic perovskite materials (CsPbX3) have attracted increasing attention due to their excellent photoelectric properties and stable physical and chemical properties. The dynamics of charge carriers affect the photoelectric conversion efficiencies of perovskite materials. Regulating carrier dynamics by changing pressure is interesting with respect to revealing the key microphysical processes involved. Here, ultrafast spectroscopy combined with high-pressure diamond anvil cell technology was used to study the generation and transfer of photoinduced carriers of a Mn-doped inorganic perovskite CsPbBr3 material under pressure. Three components were obtained and assigned to thermal carrier relaxation, optical phonon–acoustic phonon scattering and Auger recombination. The time constants of the three components changed under the applied pressures. Our experimental results show that pressure can affect the crystal structure of Mn-doped CsPbBr3 to regulate carrier dynamics. The use of metal doping not only reduces the content of toxic substances but also improves the photoelectric properties of perovskite materials. We hope that our study can provide dynamic experimental support for the exploration of new photoelectric materials.
Experimental and Computational Studies on Bio-Inspired Flavylium Salts as Sensitizers for Dye-Sensitized Solar Cells
Authors: Păușescu Iulia , Todea Anamaria , Dreavă Diana-Maria , Boboescu Tania , Pațcan Bianca , Pațcan Larisa , Albulescu Daiana , Badea Valentin , Peter Francisc , Tőtős Róbert , Ursu Daniel , Szolga Lorant , Medeleanu Mihai
Published: October 2022

Six new bio-inspired flavylium salts were synthesized and investigated by a combined computational and experimental study for dye-sensitized solar cell applications. The compounds were characterized by FT–IR, UV–Vis, NMR spectroscopy, and LC–MS spectrometry techniques. The pH-dependent photochromic properties of the flavylium dyes were investigated through a UV–Vis spectroscopy study and revealed that they follow the same network of chemical reactions as anthocyanins upon pH changes. The structural and electronic properties of the dyes were investigated using density functional theory (DFT) and time-dependent density functional theory (TD–DFT). Geometry optimization calculation revealed that all dyes, regardless of the specie, flavylium cations or quinoidal bases, present a planar geometry. The photovoltaic performances of the dyes, in both flavylium and quinoidal base forms, were evaluated by the HOMO and LUMO energies and by calculating the light-harvesting efficiencies, the free energy change of electron injection, and the free energy change regeneration. The MO analysis showed that all dyes can inject electrons into the conduction band of the TiO2 upon excitation and that the redox couple can regenerate the oxidized dyes. The results obtained for the free energy change of electron injection suggest that the quinoidal bases should inject electrons into the semiconductor more efficiently than the flavylium cations. The values for the free energy change regeneration showed that the redox electrolyte can easily regenerate all dyes. Dipole moment analysis was also performed. DSSCs based on the dyes, in both flavylium and quinoidal base forms, were assembled, and their photovoltaic performances were evaluated by measuring the open-circuit voltage, the short circuit current density, the fill factor, and the energy conversion efficiency. Results obtained by both experimental and computational studies showed that the overall performances of the DSSCs with the quinoidal forms were better than those obtained with the flavylium cations dyes.
Biocompatible Nano-Hydroxyapatites Regulate Macrophage Polarization
Authors: Zhao Da-Wang , Fan Xin-Cheng , Zhao Yi-Xiang , Zhao Wei , Zhang Yuan-Qiang , Zhang Ren-Hua , Cheng Lei
Published: October 2022

Research on regulation of the immune microenvironment based on bioactive materials is important to osteogenic regeneration. Hydroxyapatite (HAP) is believed to be a promising scaffold material for dental and orthopedic implantation due to its ideal biocompatibility and high osteoconductivity. However, any severe inflammation response can lead to loosening and fall of implantation, which cause implant failures in the clinic. Morphology modification has been widely studied to regulate the host immune environment and to further promote bone regeneration. Here, we report the preparation of nHAPs, which have uniform rod-like shape and different size (200 nm and 400 nm in length). The morphology, biocompatibility, and anti-inflammatory properties were evaluated. The results showed that the 400 nm nHAPs exhibited excellent biocompatibility and osteoimmunomodulation, which can not only induce M2-phenotype macrophages (M2) polarization to decrease the production of inflammatory cytokines, but also promote the production of osteogenic factor. The reported 400 nm nHAPs are promising for osteoimmunomodulation in bone regeneration, which is beneficial for clinical application of bone defects.
Effect of Quaternary Ammonium Salts and 1,2,4-Triazole Derivatives on Hydrogen Absorption by Mild Steel in Hydrochloric Acid Solution
Authors: Avdeev Yaroslav G. , Nenasheva Tatyana A. , Luchkin Andrey Yu. , Marshakov Andrey I. , Kuznetsov Yurii I.
Published: October 2022

The treatment of low-carbon steel items with hydrochloric acid solutions is used in many industrial technologies. This process is accompanied not only by metal corrosion losses, but also by hydrogen absorption by the metal. In this study, the kinetics of hydrogen cathodic reduction on low-carbon steel in 2 M HCl containing corrosion inhibitors, namely, quaternary ammonium salts and a 3-substituted 1,2,4-triazole, have been studied. Adsorption isotherms of corrosion inhibitors on cathodically polarized steel surface have been obtained. XPS data provide valuable information on the composition and structure of protective layers formed on steel in HCl solutions containing inhibitors. The main rate constants of the stages of gaseous hydrogen evolution and incorporation of hydrogen atoms into the metal have been determined. The addition of quaternary ammonium salts or 3-substituted 1,2,4-triazole inhibits the cathodic reduction of hydrogen and its penetration into steel in the HCl solution. 3-substituted 1,2,4-triazole is the most efficient inhibitor of hydrogen absorption. The inhibitory effect of this compound is caused by a decrease in the ratio of the hydrogen concentration in the metal phase to the degree of surface coverage with hydrogen. The maximum decrease in hydrogen concentration in the metal bulk in the presence of the 3-substituted 1,2,4-triazole is 8.2-fold, which determines the preservation of the plastic properties of steel as it corrodes in HCl solutions. The high efficiency of the 3-substituted 1,2,4-triazole as an inhibitor of hydrogen cathodic reduction and absorption results from strong (chemical) adsorption of this compound on the steel surface and the formation of a polymolecular protective layer.
Special Issue “Laser Powder Bed Fusion, Direct Energy Deposition and Hybrid Manufacturing of Metals and Alloys”
Authors: Siller Hector R.
Published: October 2022

Hybrid additive manufacturing processes involve the use of different manufacturing techniques to fabricate net shape or near-net shape parts, with enhanced capabilities of heat dissipation, such as those needed in conformal molding, or requiring internal cooling systems, such as, for example, those seen in turbine blades, and for developing other components demanding free form fabrication methods [...]
Lightweight Network with Variable Asymmetric Rebalancing Strategy for Small and Imbalanced Fault Diagnosis
Authors: Chen Biao , Zhang Li , Liu Tingting , Li Hongsheng , He Chao
Published: October 2022

Deep learning-related technologies have achieved remarkable success in the field of intelligent fault diagnosis. Nevertheless, the traditional intelligent diagnosis methods are often based on the premise of sufficient annotation signals and balanced distribution of classes, and the model structure is so complex that it requires huge computational resources. To this end, a lightweight class imbalanced diagnosis framework based on a depthwise separable Laplace-wavelet convolution network with variable-asymmetric focal loss (DSLWCN-VAFL) is established. Firstly, a branch with few parameters for time-frequency feature extraction is designed by integrating wavelet and depthwise separable convolution. It is combined with the branch of regular convolution that fully learns time-domain features to jointly capture abundant discriminative features from limited samples. Subsequently, a new asymmetric soft-threshold loss, VAFL, is designed, which reasonably rebalances the contributions of distinct samples during the model training. Finally, experiments are conducted on the data of bearing and gearbox, which demonstrate the superiority of the DSLWCN-VAFL algorithm and its lightweight diagnostic framework in handling class imbalanced data.
Lightweight Design Optimization of Nonpneumatic Tires under Radial-Stiffness Constraints
Authors: Xu Ting , Yang Jianglin , Zhu Liangliang , Gao Fei
Published: October 2022

Nonpneumatic tires (NPTs) have good safety and a good load-carrying capacity, and they replace the function of air in pneumatic tires with a solid spoke component. The radial stiffness and weight are the important indexes for evaluating the performance of an NPT. In this research, we designed an NPT according to the requirements of vehicle Chery eQ1 based on weight minimization. Taking the radial stiffness related to the bearing-capacity performance as the constraint condition, a topology-optimization algorithm is proposed to find the best thickness distribution of the spokes with the objective of minimizing the mass. First, the mechanical properties of the material were obtained with the test. Then, the FE model of an NPT with a Fibonacci spoke structure was built and validated with a radial-stiffness test on a five rigid test machine. The optimization algorithm was carried out by searching for the best thickness distribution of the spoke after verifying the reliability of the FE model. Finally, the optimized tire was manufactured, and the stiffness test was carried out to verify the feasibility of the optimization results. The results show that the spoke mass can be reduced by 9% by using the proposed optimization algorithm while satisfying the radial-stiffness constraint.
Experimental Study and Simulation-Based Criterion for Stamping Skid Line
Authors: Zhao Dewang , Zhang Chao , Zhao Kunmin , Xie Yanhao
Published: October 2022

Skid lines on the outer panels of automobiles seriously affects their appearance and are a common surface manufacturing defect. In the die and process design stages, numerical simulation is needed to predict skid lines to take prevention measures. However, it is still a challenge to predict skid lines accurately. The simulation-based skid line criteria need further verification and improvement. Therefore, this paper takes a lightweight aluminum alloy AL6061-T6 sheet as its research object, uses a set of U-shaped dies to explore the influence of process parameters on skid lines, and establishes the correlation between skid lines and surface roughness based on visual and microscopic measurements. The relationships between contact pressure/inverse bending strain and surface roughness are established through simulation. Thus, a contact pressure and inverse bending strain dependent skid line criterion is constructed. The skid line criterion based on the simulation results has theoretical, guiding significance for the practice of engineering.
Experimental Study on the Influence of Micro-Abrasive and Micro-Jet Impact on the Natural Frequency of Materials under Ultrasonic Cavitation
Authors: Song Tianjiao , Zhu Xijing , Ye Linzheng , Zhao Jing
Published: October 2022

The higher the natural frequency of the material is, the more resistant it is to deformation under impulse loading. To explore the influence of micro-abrasive and micro-jet impact on the natural frequency and resonance amplitude value of the material under ultrasonic cavitation, 18 sets of single-factor controlled variable ultrasonic cavitation experiments were carried out on a polished specimen of 6061 aluminum alloy (30 mm × 30 mm × 10 mm). With the increase of the abrasive content in the suspension, the natural frequency of the workpiece first increased, then decreased and remained stable. With the increase of the ultrasonic amplitude, the resonance amplitude value of the material increased, reaching the maximum at 0.1789 m·s−2 and then decreased. The effect of ultrasonic amplitude on the natural frequency of the material was greater than that of the abrasive content, and the effect of the abrasive content on the common amplitude value was greater than that of the ultrasonic amplitude. This research provides a certain reference significance for exploring the influence of power ultrasonic micro-cutting on material properties and avoiding the occurrence of resonance phenomenon of the workpiece under different working conditions.
Feature-Based MPPI Control with Applications to Maritime Systems
Authors: Homburger Hannes , Wirtensohn Stefan , Diehl Moritz , Reuter Johannes
Published: October 2022

In this paper, a novel feature-based sampling strategy for nonlinear Model Predictive Path Integral (MPPI) control is presented. Using the MPPI approach, the optimal feedback control is calculated by solving a stochastic optimal control (OCP) problem online by evaluating the weighted inference of sampled stochastic trajectories. While the MPPI algorithm can be excellently parallelized, the closed-loop performance strongly depends on the information quality of the sampled trajectories. To draw samples, a proposal density is used. The solver’s and thus, the controller’s performance is of high quality if the sampled trajectories drawn from this proposal density are located in low-cost regions of state-space. In classical MPPI control, the explored state-space is strongly constrained by assumptions that refer to the control value’s covariance matrix, which are necessary for transforming the stochastic Hamilton–Jacobi–Bellman (HJB) equation into a linear second-order partial differential equation. To achieve excellent performance even with discontinuous cost functions, in this novel approach, knowledge-based features are introduced to constitute the proposal density and thus the low-cost region of state-space for exploration. This paper addresses the question of how the performance of the MPPI algorithm can be improved using a feature-based mixture of base densities. Furthermore, the developed algorithm is applied to an autonomous vessel that follows a track and concurrently avoids collisions using an emergency braking feature. Therefore, the presented feature-based MPPI algorithm is applied and analyzed in both simulation and full-scale experiments.
Machining Performance for Ultrasonic-Assisted Magnetic Abrasive Finishing of a Titanium Alloy: A Comparison with Magnetic Abrasive Finishing
Authors: Ma Fujian , Wang Ziguang , Liu Yu , Sha Zhihua , Zhang Shengfang
Published: October 2022

Titanium alloys are widely used in aerospace, the military industry, electronics, automotive fields, etc., due to their excellent properties such as low density, high strength, high-temperature resistance, and corrosion resistance. Many components need to be finished precisely after being cut in these applications. In order to achieve high-quality and high-efficiency finishing of titanium alloys, ultrasonic-assisted magnetic abrasive finishing (UAMAF) was introduced in this research. The machining performance for UAMAF of a titanium alloy was studied by experimentally comparing UAMAF and magnetic abrasive finishing (MAF). The results show that the cutting force of UAMAF can reach 2 to 4 times that of MAF, and it decreases rapidly with the increase in the machining gap due to the energy loss of ultrasonic impact in the transmission between magnetic abrasives. The surface roughness of UAMAF can reach about Ra 0.075 μm, which is reduced by about 59% compared with MAF. The main wear type of the magnetic abrasive is that the diamond grits fell off the magnetic abrasive in both UAMAF and MAF. The uniform wear of the magnetic abrasive is realized, and the utilization ratio of the magnetic abrasive is obviously improved in UAMAF.
Improving the Force Display of Haptic Device Based on Gravity Compensation for Surgical Robotics
Authors: Jin Lixing , Duan Xingguang , He Rui , Meng Fansheng , Li Changsheng
Published: October 2022

Haptic devices are applied as masters to provide force displays for telemedicinal robots. Gravity compensation has been proven to be crucial for the accuracy and capability of force displays, which are critical for haptic devices to assist operators. Therefore, the existing method suffers from an unsatisfactory effect, a complex implementation, and low efficiency. In this paper, an approach combining active and passive gravity compensation is proposed to improve the performance of a force display. The passive compensation is conducted by counterweights fixed with the moving platform and pantographs to offset most of the gravity and reduce the loads of the motors, while the peak capability of the force display is enhanced. The required weight is optimized by a multi-objective genetic algorithm in terms of the maximum torque of the motors in the global workspace. As a supplement, the residual gravity is eliminated by active compensation to extend the accuracy of the force display. The balancing forces in the discretized workspace are entirely calibrated, and the required force for the arbitrary configuration is calculated by interpolations. The decisions regarding the algorithm parameters are also discussed to achieve a compromise between the effect and elapsed time. Finally, the prototype with a compensation mechanism is implemented and experiments are carried out to verify the performance of the proposed method. The results show that the peak capability of the force display is enhanced by 45.43% and the maximum deviation is lowered to 0.6 N.
Effects of Coolant and Working Temperature on the Cavitation in an Aeronautic Cooling Pump with High Rotation Speed
Authors: Wu Ao , Zhao Ruijie , Wang Fei , Zhang Desheng , Wang Xikun
Published: October 2022

The centrifugal pump with high rotation speed is the key component in the cooling system of an aircraft. Because of the high rotation speed, the impeller inlet is very prone to cavitation. Two impellers with different types of blades (cylindrical and splitter) are designed, and the numerical models of the pumps are built. The authenticity of the numerical models is validated with the corresponding experiments in terms of both the hydraulic and cavitation characteristics. Then, the effects of different coolants and working temperatures on the hydraulic and cavitation performances of the prototype models are studied based on the numerical simulations. The results show that the head and efficiency of the pump for conveying water are higher than those for conveying ethylene glycol (EG) aqueous solution and propylene glycol (PG) aqueous solution (EGaq and PGaq are defined to represent the EG aqueous solution and the PG aqueous solution, respectively). The hydraulic performance in the EGaq is slightly better than that in the PGaq. The cavitation performance of water is far less than that of the EGaq and PGaq under high working temperature. The volume of cavitation in EGaq is smaller than that in PGaq, and the volume of cavitation in the splitter blades is slightly smaller than that in the cylindrical blades. It is suggested that EGaq be used as the first option. The splitter blades can improve the cavitation performance somehow while the improvement by using the splitter blades is very limited at high rotation speeds, and the design of the short blades should be careful in order to obtain a smooth internal flow field.
A Reverse Modeling Method Based on CAD Model Prior and Surface Modeling
Authors: Fan Linlin , Wang Junyi , Xu Zhigang , Yang Xiao
Published: October 2022

Reverse engineering is an important process of real model digitization. However, the existing methods are limited by the characteristics of the modeling object; the modeling is low efficient, has poor versatility, and unstable accuracy. To complete the reverse engineering of a real workpiece with irregular deformation based on the ideal computer-aided design (CAD) model, a high-precision reverse engineering method of the workpiece based on the CAD model prior was presented. Through the registration of the ideal CAD model and the point cloud model of the real workpiece, the geometric feature position information and feature constraint information contained in the CAD model are transmitted to the modeling process, which helps to improve the accuracy and efficiency of reverse engineering. This method is applied to the reverse engineering process of the engine compartment with slight irregular deformation, the modeling accuracy reaches 0.04 mm, and the high-precision reverse engineering of the engine compartment is successfully realized.