Small Amount Research Articles

Determining the influence of technological parameters of electron beam surfacing process on the microstructure and microhardness of Ti-6Al-4V alloy

This paper reports the devised technology and equipment for manufacturing parts and assemblies with pre-defined properties by 3D printing methods. Underlying the technology is the application of a high-power electron beam to fuse metal powder in a vacuum chamber with the formation of successive layers that repeat the contours of the digital model of the product. The object of research is the process of surfacing products made of Ti6Al4V titanium alloy powder. The influence of technological parameters (speed and power of the electron beam) on the formation of the structure of the deposited metal and its mechanical properties was investigated. 3 samples printed under 3 modes were studied: beam speed, 270, 540, and 780 mm/s; power, 240, 495, and 675 W, respectively. The beam energy density was 44.5 J/mm3; the trajectory displacement step was 0.2 mm; the dynamic focusing current Idf was –0.31 A; and the powder layer thickness was 0.1 mm. The samples were examined by conventional methods. The structures were studied using an optical microscope, images were recorded with a camera. The Vickers hardness was measured with a microhardness meter in the direction from the technological supports to the surface of the sample, as well as along the surface of the product, and in the layers of the middle part of the sample. It was established that the articles had a dense cast structure of surfaced metal. On all samples, large crystallites with a uniform lamellar-acicular structure of α´-phase with a small amount of β-phase are formed along the height, mostly without defects with uniform microhardness both along the height and along the surface. It was determined that the surfacing mode at beam speed, 240 mm/s; power, 270 W is the most rational for practical use. Under this mode, a stronger structure is formed when it is crushed, reducing the width of the crystallites by 1.55 and 1.17 times compared to other modes

Strengthening reinforced concrete bridge piers against heavy vehicle collisions with ultra-high performance concrete collars: A finite element analysis study

This paper investigates the effectiveness of ultra-high performance concrete (UHPC) collars in strengthening reinforced concrete (RC) bridge piers against heavy tractor-trailer collisions through finite element (FE) analysis. First, validated FE models of UHPC and a heavy tractor-trailer were provided. Then, FE analyses were conducted to evaluate the strengthening performance of the UHPC collar. The effectiveness of UHPC collar was compared with conventional RC collar, and the effects of varying UHPC collar thickness, height, and collar reinforcement were investigated. The results showed that the most severe damage observed on bridge piers due to heavy vehicle collisions primarily occurred below a height of approximately 2000 mm, manifested as diagonal shear cracks and plastic hinges. Therefore, the recommended minimum collar height is 2000 mm. The comparison between UHPC collar and RC collar strengthening demonstrated the superior effectiveness of UHPC collars. A 130-mm UHPC collar exhibited a similar strengthening effect as an 180-mm RC collar. Among the three investigated parameters of UHPC collar thickness, height, and collar reinforcement, the study found that collar thickness had the most significant influence on the effectiveness of the UHPC collar in terms of damage pattern, energy absorption, and maximum deflection. While collar height primarily influenced deflection, a larger collar height was beneficial in reducing pier deflection at the end of the strengthened segment. Adding a small amount of collar reinforcement improved the performance of piers; however, this improvement was limited. The findings of this study address the lack of research on using UHPC for strengthening full-scale bridge piers against heavy tractor-trailer collisions and provide valuable references for future designs with similar applications.

Transformation and metabolism impact of ZnO-NPs on microalgal-bacterial granular sludge

Although the hazards of zinc oxide particles (ZnO-NPs) in the field of wastewater treatment are receiving more and more attention, the responses of metabolism and migration pathways of microalgal-bacterial symbiosis to ZnO-NPs have not been well understood. Here, the distribution of ZnO-NPs along with its impact on metabolism in microalgal-bacterial granular sludge (MBGS) was studied. The results showed that over 95% of ZnO-NPs in the MBGS system were absorbed by sludge or enriched in the sludge layer in the form of zinc oxide, while releasing a small amount of Zn2+. The adsorption of ZnO-NPs by MBGS mainly relied on the –OH functional groups and protein structures. After ZnO-NPs adsorption, the cell membrane could be destroyed, resulting in the release of lactate dehydrogenase. At the genetic level, ZnO-NPs promoted gene abundance levels related to biological processes and enzyme glycosyl transferase synthesis, but inhibited intracellular biosynthesis and metabolism of genetic material, especially glutathione synthesis. Key functional and biosynthetic genes involved in metabolic processes were also inhibited, such as acs and glnA. This study explained in detail how ZnO-NPs altered and impacted on MBGS, which provided a reference for future practical applications of MBGS for wastewater treatment containing nanoparticles.

A Bilingual Basque–Spanish Dataset of Parliamentary Sessions for the Development and Evaluation of Speech Technology

The development of speech technology requires large amounts of data to estimate the underlying models. Even when relying on large multilingual pre-trained models, some amount of task-specific data on the target language is needed to fine-tune those models and obtain competitive performance. In this paper, we present a bilingual Basque–Spanish dataset extracted from parliamentary sessions. The dataset is designed to develop and evaluate automatic speech recognition (ASR) systems but can be easily repurposed for other speech-processing tasks (such as speaker or language recognition). The paper first compares the two target languages, emphasizing their similarities at the acoustic-phonetic level, which sets the basis for sharing data and compensating for the relatively small amount of spoken resources available for Basque. Then, Basque Parliament plenary sessions are characterized in terms of organization, topics, speaker turns and the use of the two languages. The paper continues with the description of the data collection procedure (involving both speech and text), the audio formats and conversions along with the creation and postprocessing of text transcriptions and session minutes. Then, it describes the semi-supervised iterative procedure used to cut, rank and select the training segments and the manual supervision process employed to produce the test set. Finally, ASR experiments are presented using state-of-the-art technology to validate the dataset and to set a reference for future works. The datasets, along with models and recipes to reproduce the experiments reported in the paper, are released through Hugging Face.

Ensemble coding of multiple facial expressions is not affected by attentional load.

Human observers can extract the mean emotion from multiple faces rapidly and precisely. However, whether attention is required in the ensemble coding of facial expressions remains debated. In this study, we examined the effect of attentional load on mean emotion processing with the dual-task paradigm. Individual emotion processing was also investigated as the control task. In the experiment, the letter string and a set of four happy or angry faces of various emotional intensities were shown. Participants had to complete the string task first, judging either the string color (low attention load) or the presence of the target letter (high attention load). Then a cue appeared indicating whether the secondary task was to evaluate the mean emotion of the faces or the emotion of the cued single face, and participants made their judgments on the visual analog scale. The results showed that compared with the color task, the letter task had a longer response time and lower accuracy, which verified the valid manipulation of the attention loads. More importantly, there was no significant difference in averaging performance between the low and high attention loads. By contrast, the individual face processing was impaired under the high attention load relative to the low attentional load. In addition, the advantage of extracting mean emotion over individual emotion was larger under the high attentional load. These results support the power of averaging and provide new evidence that a rather small amount of attention is needed in the ensemble coding of multiple facial expressions.

Preparation and investigation of two-component silica-modified hydrophobic layer for minimizing retention loss of reversed-phase chromatographic columns using fully aqueous mobile phases

Chromatographers often employ fully aqueous mobile phases to retain highly polar compounds in reversed-phase liquid chromatography (RPLC). However, when the flow rate is interrupted, either accidentally or intentionally, a substantial loss in retention occurs due to the spontaneous dewetting of water from the hydrophobic surface of conventional RPLC-C18 particles. Previous studies have shown that maintaining a low C18 surface coverage (approximately 1.5 μmol/m2) can mitigate water dewetting by increasing chain disorder, facilitating the intercalation of water clusters between the C18-bonded chains, and keeping the mesopores wetted. In this research, we explore the potential and additional benefits of using two-component surface bonding materials (C8/C18 and PhenylHexyl (PhHx)/C18) at a constant and low total surface coverage of 1.51 ± 0.15 μmol/m2. We synthesized seven one- and two-component modified silica particles with a volume average particle size of 5.22 μm and an average mesopore size of 104 Å. The surface coverage was increased from 0 to 0.54, 1.00, and to 1.66 μmol2 for C8 chains and from 0 to 0.52, 0.70, and to 1.65 μmol2 for PhHx ligands. To prevent interactions between water and any unreacted silanols, all seven derivatized particles were heavily endcapped with trimethylsilane (TMS) reagent. The fraction of the surface area remaining in contact with water was determined by measuring the retention times of weakly (thiourea) and strongly (thymine) retained compounds at intervals of 1, 2, 4, 8, 16, 32, and 64 minutes following the cessation of flow. Two distinct column temperatures, 24°C and 60°C, were employed in the experiments. Retention losses were found to be minimized in the presence of a small quantity of C8 chains (less than 40% of the total surface coverage). Additionally, it is essential to consider substantial fractions of PhHx chains, as long as the presence of the PhHx ligand does not significantly impact retention and selectivity. Combining mixed RPLC bondings with a low total surface coverage of approximately 1.5 μmol/m2 emerges as a viable solution for further minimizing retention loss in standard C18-bonded RPLC columns, particularly within the surface coverage range of 2.5-3.0 μmol/m2.

Diagenetic controls over reservoir quality of tight sandstone in the lower Jurassic reservoir in the Lenghu area, the north margin of Qaidam basin

The Lower Jurassic Reservoir (LJR) in the Lenghu area on the northern margin of the Qaidam Basin (NMoQB) has become the most promising target for hydrocarbon exploration. The reservoir has experienced complex diagenesis; however, the porosity evolution and the influence of different diagenesis events on reservoir densification remains unclear. In this study, various analytical methods was first used to clarify the diagenetic stage and sequence, establish a porosity evolution model, quantitatively analyze the time and influence of different diagenesis events on reservoir densification, and illustrate the densification mechanism of tight sandstone reservoir in the Lenghu area. The results showed that the dominant rock types in the LJR were feldspathic litharenite, followed by litharenite, lithic arkose, and a small amount of subarkose and sublitharenite. The reservoir is a typical tight sandstone reservoir (TSR), with average porosity and permeability of 5.5% and 0.08 mD, respectively. The pore types were primarily secondary pores, followed by residual intergranular pores and occasional fractures. Diagenesis of LJR has entered the meso-diagenetic stage A, with minor progression into meso-diagenetic stage B. Quantitative calculation showed that the initial porosity of LJR is 32.2%. In eo-diagenetic stage A, compaction is the main factor for porosity reduction. In eo-diagenetic stage B, the porosity loss rates caused by compaction and cementation were 81.5% and 11.8%, respectively. In this stage, the LJR in the Lenghu area has almost been densified, mainly affected by compaction, calcite cementation and clay minerals cementation. Additionally, cementation is an important factor causing reservoir heterogeneity and is dominated by calcite and clay mineral cementation. After entering the meso-diagenetic stage A, dissolution is the main diagenesis event, which can increase porosity by 6.0%. This stage is the critical period for forming high-quality reservoir of LJR in the Lenghu area, mainly in the 4,400 m depth. In meso-diagenetic stage B, the influence of dissolution gradually decreased. Simultaneously, in this stage, the cementation of iron-bearing calcite further strengthened the densification of the LJR in the Lenghu area.

Dielectric and mechanical properties of porous Si3N4–Kovar composites prepared by low‐temperature oxidation sintering

AbstractThe aim of this study is to investigate the impact of the Kovar glass content on the mechanical and electrical properties of Si3N4–Kovar composites sintering at air atmosphere. To achieve this, Si3N4–Kovar composites were prepared using molding technology with the Kovar glass powder ranging from 20 to 70 wt%. The phase composition, morphology, bulk density, apparent porosity, flexural strength at room temperature, dielectric constant, and dielectric loss of the composites were all examined in relation to changing the Kovar glass content. During the sintering process, the α‐quartz on the surface of Si3N4 particles acted as the crystal nucleus, inducing the crystallization of the glass at the wetting position that the Kovar glass and the surface of the Si3N4 particles. A small amount of the β‐quartz phase was crystallized at 750–850°C, followed by a large amount of the β‐quartz phase crystallizing above 900°C. Additionally, some β‐quartz phase transformed into the metastable β‐cristobalite phase that could exist below 1470°C. During the cooling process, the β‐cristobalite phase transformed into a low‐temperature α‐cristobalite phase, while the β‐quartz phase transformed into a low‐temperature α‐quartz phase. The results indicate that the Si3N4–Kovar glass composite with 60 wt% the Kovar glass content sintered at 900°C exhibits higher density (1.88 g/cm3), lower porosity (25.4%), higher flexural strength (55.34 MPa), lower dielectric constant (3.46), and lower dielectric loss (4.26 × 10−3).

Motion-artifact-augmented pseudo-label network for semi-supervised brain tumor segmentation

MRI image segmentation is widely used in clinical practice as a prerequisite and a key for diagnosing brain tumors. The quest for an accurate automated segmentation method for brain tumor images, aiming to ease clinical doctors’ workload, has gained significant attention as a research focal point. Despite the success of fully supervised methods in brain tumor segmentation, challenges remain. Due to the high cost involved in annotating medical images, the dataset available for training fully supervised methods is very limited. Additionally, medical images are prone to noise and motion artifacts, negatively impacting quality. In this work, we propose MAPSS, a motion-artifact-augmented pseudo-label network for semi-supervised segmentation. Our method combines motion artifact data augmentation with the pseudo-label semi-supervised training framework. We conduct several experiments under different semi-supervised settings on a publicly available dataset BraTS2020 for brain tumor segmentation. The experimental results show that MAPSS achieves accurate brain tumor segmentation with only a small amount of labeled data and maintains robustness in motion-artifact-influenced images. We also assess the generalization performance of MAPSS using the Left Atrium dataset. Our algorithm is of great significance for assisting doctors in formulating treatment plans and improving treatment quality.

High-throughput synthesis and oxidation behavior of a continuous composition spread (Nb–Ti)1-x-ySixCry alloy thin film

High-throughput method of three targets magnetron sputter co-deposition was adopted to prepare (Nb–Ti)1-x-ySixCry composition spread alloy film (CSAF). Early oxidation behavior of the as-deposited alloy thin film was investigated in atmospheric conditions at 1250 °C for 10 min. A (Nb–Ti)1-x-ySixCry combinatorial material library covering (9.34–32.31) Si-(10.43–20.27) Cr (at. %) is obtained and as-deposited film was composed of amorphous phase. The oxidized film was separated into three regions having different oxidation products. The composition range for establishment of a protective scale (SiO2 and CrNbO4) and a small amount of Nb2O5 was ascertained efficiently across the entire alloy thin film.

Preparation and Application of Apatite-TiO2 Composite Opacifier: Preventing Titanium Glaze Yellowing through Pre-Combination.

In order to enhance the degree of binding reaction of TiO2 in titanium-containing ceramic glazes and prevent the reaction of its transformation into rutile to eliminate the yellowing phenomenon of the glaze surface, an apatite-TiO2 composite opacifier (ATO) was prepared through the mechanical grinding of hydroxyapatite and anatase TiO2. The properties, opacification mechanism, and yellowing inhibition of the prepared ceramic glazes were studied. The results show that the ATO is characterized by a uniform coating of TiO2 on the surface of the apatite and the formation of close chemical bonding between the apatite and TiO2. The ceramic glaze surface when using an ATO has a white appearance and excellent opacification performance. When an ATO was used, the L*, a*, and b* values of the glaze were 89.99, -0.85, and 3.37, respectively, which were comparable to those of a ZrSiO4 glaze (L*, a*, and b* were 88.24, -0.02, and 2.29, respectively). The opacification of the glaze was slightly lower than that of the TiO2 glaze (L* value was 92.13), but the appearance changed from yellow to the white of the TiO2 glaze (b* value was 9.18). The ceramic glaze layer when using an ATO mainly consists of titanite, glass phase, and a small amount of quartz, and the opacification mechanism is the crystallization of the generated titanite. ATOs can play an active role in solving the critical problem that arises when TiO2 replaces ZrSiO4 as an opacifier.

Mechanical properties and field test of lime-soda residue stabilized soil for subgrade

To broaden the sources of subgrade filler and the utilization of Soda Residue (SR), SR was employed to modify clay by adding a small amount of lime for further stabilization, forming a Lime-Soda-Residue-Stabilized Soil (LSRSS). A set of intensive research paths was established, from testing of laboratory mechanical property, mechanism disclosure, and field verification to operational effect. Through Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR), and Resilient Modulus (MR) experiments, it was concluded that with the increase in SR content, the UCS, CBR, and MR values of LSRSS showed an increasing trend then followed by a decrease, reaching their peak values, respectively of 0.62 MPa, 65.0%, 78.83 MPa, all at 30% SR content. An optimal proportion was determined for LSRSS as 6% lime, 30% SR, and 70% clay. The UCS, CBR, and MR values of optimal proportion all increased with the increase of compaction degree, but increased first and then decreased with the increase of water content. Their maximum values did not correspond to the OWC of 23% but to 27%, called the compaction water content, which was suitable for application in the actual LSRSS subgrade. Field test results showed that the UCS, CBR, and MR values were 0.85 MPa, 86.5%, and 135.7 MPa, which all were higher than the laboratory values, and the long-term road performance was outstanding. The analysis demonstrates that the better strength and road performance of LSRSS are mainly determined by the superior gradation and the reaction of three materials. The laboratory and field test results collectively provide data evidence for excellent performance and lay a solid foundation for the wider application of the LSRSS subgrade.

Mechanical Properties of Ti3AlC2/Cu Composites Reinforced by MAX Phase Chemical Copper Plating.

Among the various reinforcement phases available in Cu-based composites, the unique layered structure and easy diffusion of A-layer atoms make MAX phases more suitable for reinforcing a copper matrix than others. In this study, Cu-coated Ti3AlC2 particles (Cu@Ti3AlC2) were prepared through electroless plating, and Cu@Ti3AlC2/Cu composites were fabricated via vacuum hot-press sintering. The phase composition and microstructure of both Cu@Ti3AlC2 powder and composites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results demonstrate the creation of successful electroless copper plating to obtain a Cu coating on Ti3AlC2 particles. At 850 °C, a small amount of Ti3AlC2 particles decompose to form TiCx, while Al atoms from the A layer of MAX phase diffuse into the Cu matrix to form a solid solution with Cu(Al). The test results reveal that the density of the Cu@Ti3AlC2/Cu composite reaches 98.5%, with a maximum compressive strength of 705 MPa, which is 8.29% higher than that of the Ti3AlC2/Cu composite. Additionally, the compressive strain reaches 37.6%, representing an increase of 12.24% compared to that exhibited by the Ti3AlC2/Cu composite.

Study on Al2O3/Fe-Al gradient coating assisted prepared by ionic liquid for Lead-Bismuth eutectic corrosion resistance

Alumina coating which has excellent corrosion resistance to lead–bismuth eutectic (LBE) is very promising to be used in future LBE cooling system. In this paper, the Al2O3/Fe-Al gradient coating is prepared on the surface of SIMP steel assisted by ionic liquid aluminum electroplating and subsequent heat treatments and selective oxidation. The protective Al2O3 layer is composed of much γ-phase and a small amount α-phase. The Fe-Al transition layer is mainly composed of FeAl alloy phase. After being exposed for 600 h to LBE at 600 °C, the coating still maintains intact and dense structure and good compatibility to the substrate, effectively preventing the substrate steel from the corrosion attack of LBE. While obvious LBE attack can be observed in the compared bare steel. Finally, to verify the possibility of this approach preparing Al2O3/Fe-Al coating on complex geometries, we have also successfully prepared this sort of coating on the inner surface of a steel tube, indicating that this coating has a great application potential in the future.

Formation and strengthening mechanism of equiaxial cellular grain zone in AA2195-T8 Al–Cu–Li alloy twin-wire P-VPPA welded joint with Ti–Zr microalloying

A novel method involving twin-wire pulsed VPPA (P-VPPA) welding was combined with Ti–Zr microalloying to improve the mechanical properties of AA2195-T8 Al–Cu–Li alloy variable polarity plasma arc (VPPA) welded joints. This method aimed to increase the width of the equiaxial cellular grain zone (ECZ) by adding higher content of Ti–Zr and reducing heat input. The microstructure evolution process was established to understand the formation and strengthening mechanism of the ECZ. The results showed that the strength of the ECZ was higher than that of the dendrite in the weld zone (WZ). The twin-wire VPPA welding led to the formation of a wider ECZ near the fusion zone (FZ). This ECZ was continuously distributed throughout the thickness direction of the welded joint. Combined with higher Ti–Zr microalloying, the maximum width of ECZ increased to 2.5 mm and extended to the WZ. Consequently, the proportion of cracks passing through the ECZ during tensile fracture increased from 27.6% to 88.7%. Moreover, the ultimate tensile strength (UTS) of the welded joint exhibited a notable improvement, rising from 328 MPa to 370 MPa, while the elongation also increased to 5%. The UTS of the welded joint achieved 66% of the base metal. Additionally, the average grain size in the ECZ was 14 μm. The formation of the ECZ was primarily attributed to the nucleation precursors of Al3(Ti, Zr) and β′ phase, as well as less welding heat input near the FZ. The widening of the ECZ was mainly due to the presence of more Al3(Ti, Zr) phases. Moreover, the grain boundary of the ECZ exhibited the distribution of Al–Cu eutectic, θ(Al2Cu), Ω, T2(Al6CuLi3), and ω(Al7Cu2Fe) phases, while a small amount of T1(Al2CuLi) phase precipitated within the grain. The strengthening mechanism of ECZ is the result of multiple strengthening effects, including the reduction of element segregation and microcracks, the precipitation of the T1 phase, and the fine grain strengthening.

Comet 81P/Wild 2 dust impactors of Stardust turnip-like tracks analogous to cluster IDPs

We measured oxygen isotope ratios of 16 silicate fragments from seven aerogel tracks (turnip-like type B tracks 77, 149, 172, 191, and 220; carrot-like type A tracks 22 and 175) of the comet 81P/Wild 2 collector from NASA’s Stardust mission using secondary ion mass spectrometry. Thirteen were prepared by ultramicrotomy; three from track 220 were prepared by sputtering resin blocks using a SIMS Kohler beam, a new procedure aiming to mine as many cometary particles encased in aerogel/resin as possible. Combining new and literature results, we recognized that most silicate fragments of individual type B tracks have diverse mineralogy but consistent mass-independent fractionation of oxygen isotopes (Δ17O = δ17O − 0.52 × δ18O). These observations suggest that their impactors are loosely bound aggregates of unequilibrated materials originating mainly from similar protoplanetary disk regions, resembling the cluster IDP U2-20-GCA. Furthermore, silicate fragments from type A track 22 have almost identical mineralogy and Δ17O values, confirming that its impactor is a single chondrule-like fragment. The terminal particle of type A track 175 is pure forsterite with Δ17O of ∼ –23 ‰.Six iron-rich fragments of this study have positive oxygen isotope ratios (Δ17O∼ +2 ‰) and ordinary chondrite chondrule-like olivine compositions. Together with five similar fragments in the literature, a unique population (Mg# ≤ 86) of Wild 2 fragments that resemble chondrules from the inner solar system (O-E-R) chondrites or the outer solar system CH-CB chondrites was identified. The remaining 16O-poor Wild 2 fragments are Mg# ≥ 79 silicates with Δ17O ∼ –2 ‰ and a small amount of Mg# ≤ 79 silicates with Δ17O ∼ 0 ‰, which are most consistent with CR chondrite chondrules. Thus, we conclude that in addition to the possible major source of CR chondrite chondrule-like materials, the inner solar system or CH-CB chondrule-like materials are a minor component of comet Wild 2, like the cluster IDP U2-20-GCA.

Thermal regulation of photovoltaic panels using shape-stabilized phase change materials supported by exfoliated graphite/graphene nanofillers

This experimental research focuses on using shape-stabilized phase change materials (SS-PCMs) for thermal management of a PV panel. SS-PCMs are composed of 50% beeswax and 50% coconut oil, and exfoliated graphite (xGnP)/graphene (GP) nanoparticles to enhance shape-stabilization and thermal conductivity of the SS-PCM. The influence of weight fraction of xGnP/GP (φ = 0, 2.5, 5, 7.5, and 10%wt) and weight fraction ratio of GP to xGnP (α = 1/1, 1/3, 1/5, 1/7, and 1/9) on the performance of PV panel are evaluated. The results demonstrated that using the SS-PCMs, maximum temperature reduction of PV panel is from 60.52 °C to 44.06 °C, while it is 57.62 °C for PCM without nanofillers. It is identified that φ = 10% shows the minimum temperature and maximum electrical efficiency for the PV panel. However, the difference between PV temperature and electrical efficiency for φ = 7.5 and φ = 10 are not very remarkable. A small amount of GP and xGnP with α = 1/3 achieved the more shape-stabilized and high thermal conductivity PCMs. Finally, SS-PCMs with φ = 10 and α = 1/3 had maximum electrical efficiency of 13.50% and power of 80.15 W.

Evolution of Fe-bearing phases during the fabrication and its effect on the mechanical properties of AA8014 aluminum alloy

The morphology of Fe-bearing phase particles has significant influences on the mechanical properties of AA8014 aluminum alloy sheets. This study aims to investigate the evolution of the morphology, size, and distribution of Fe-bearing phases during casting, homogenization, and rolling. In the paper, the effects of thermal treatment and deformation on the evolution of the Fe-bearing phases, and the mechanical properties of AA8014 aluminum alloy annealing sheet have been studied quantitatively. The main phase components in the ingot are α-Al matrix, Al6(Fe,Mn), and a small amount of Al3(Fe,Mn) and α-Al(Fe,Mn)Si. Homogenization at 630℃ for 12 h leads to the transformation of the metastable Al6(Fe,Mn) particles into stable α-Al(Fe,Mn)Si with “pore structures”. Subsequent hot rolling (75.0 mm to 7.0 mm, deformation rate of 91%) results in a significant increase in the area number density of Fe-bearing particles, accompanied by a notable decrease in average length and aspect ratio, leading to a more uniform distribution of Fe-bearing phases. Cold rolling (7.0 mm to 0.7 mm, deformation rate of 90%) or further annealing causes slight changes in the area number density and size of Fe-bearing phases. Notably, the content of α-Al(Fe,Mn)Si is minimal in the non-homogenized ingot. After hot rolling and cold rolling, the coarse Fe-bearing particles are observed in the non-homogenized sheets with 7.0 mm and 0.7 mm thickness, with a non-uniform distribution of the Fe-bearing phases. A comparative study was conducted on the mechanical properties and microstructure in final sheets with 0.7 mm thickness fabricated from homogenization and non-homogenization. The yield strength, ultimate tensile strength, elongation, and work hardening exponent in sheet with homogenization are higher due to smaller grain and Fe-bearing phase particles.

Graphene oxide assisted preparation of V2O5 films for electrochromic and energy storage applications

A V2O5 film is prepared by an electrochemical deposition method with the assistance of graphene oxide (GO). The surface morphology and microstructure of the film are characterized by scanning electron microscope, X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy measurements. The results demonstrate that the prepared film is mainly composed of orthorhombic α-V2O5 with a small amount of tetragonal β-V2O5; the V2O5 film has a wrinkled surface morphology and contains a certain low valance V4+ and a trace amount of graphene oxide residue. The V2O5 film exhibits good lithium storage activity and excellent cycling stability (with a capacity retention rate of 93.6% after 500 cycles at 0.5 mA cm−2). During lithium intercalation and de-intercalation processes, the color of the V2O5 film changes reversibly from yellow to green, and finally blue, with a fast response time (6∼9 s) and high coloration efficiency (19.77 cm2 C−1). In addition, the electrochromic device assembled with the V2O5 film as the electrochromic layer, NiHCF as the ion storage layer, and 1 M LiClO4/propylene carbonate solution as the electrolyte also exhibits excellent cycling stability, suggesting the significant potential of this V2O5 film for electrochromic and energy storage applications.

Evaluating the Impact of Using HEFA Fuel on the Particulate Matter Emissions from a Turbine Engine

The dynamically growing sustainable aviation fuel (SAF) industry and the implemented European policy create the need for conducting research on the actual benefits of using alternative fuels in aviation. The aim of this research was to assess the impact of HEFA (hydroprocessed esters and fatty acids) fuel on the particulate matter emission indicators of an aircraft engine. This article presents the results of the measurements of particle emissions from a jet engine fueled by a blend of aviation kerosene and HEFA fuel (with HEFA content at 5%, 20%, and 30% by volume). A positive effect of HEFA on both the number and mass indices of particles was observed. The use of SAF fuel led to a reduction in the particulate number index by 90% and the particulate mass index by 75%. The Particle Number Emission Index (EIN) for an engine fueled with Jet A-1 exhibited values ranging from 5.23 × 1016 to 1.33 × 1017 particles per kilogram. The use of HEFA fuel (30% content) allowed for a reduction in the EIN to the range of 2.83 × 1015 to 1.04 × 1016 particles per kilogram. A detailed analysis of particle size distribution (PSD) for both the number and volume of particles was conducted. It was noted that neither the fuel composition nor the engine operating parameters significantly affected the shape of the PSD, but the use of HEFA fuel distinctly reduced the values of the number-based PSD. It was observed that the volume-based PSD had a bimodal shape, indicating a significant contribution of particles larger than 100 nm, forming the so-called soot mode. Our findings suggest that even a small amount of HEFA fuel yields satisfactory results in reducing particulate matter emissions.