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The fatigue performance of hard asphalt is an important factor that affects the service life of asphalt pavement. In order to comprehensively explore the influence of chemical components on the fatigue performance of hard asphalt, and to eliminate the chemical instability between the microstructure of asphalt from different oil sources, seven kinds of hard asphalt were designed and prepared with saturates, aromatics, resins, and asphaltenes (SARA) extracted from the same hard asphalt. Rheological, time sweep and linear amplitude sweep (LAS) tests were carried out to evaluate the fatigue properties. The results show that the complex modulus of asphalt binds increased rapidly with an increase of asphaltene and resins and that the colloidal structure was strengthened, which would increase the fatigue factor. In the time sweep test, the strength of the colloidal structure significantly affected the fatigue life, and the fatigue life was different under different test stresses. In the viscoelastic continuum damage (VECD) model, the cumulative damage was related to the modulus, while with the increase of asphaltene and resins, the fatigue life showed a trend of first increasing and then decreasing. The linear regression analysis showed that the fatigue life of hard asphalt had a good correlation with strain sensitivity. This study investigated the applicability of different fatigue evaluation methods and revealed the influence of four components on the fatigue properties of hard asphalt. The results provide significant insights in the improvement of the fatigue performance of both hard asphalt and corresponding mixtures.

The effects of rare earth erbium (Er) micro-additions on the microstructures and mechanical properties of 2024 aluminum alloy were investigated. The microstructures and fracture surfaces of specimens prepared via high-energy ball milling, cold isostatic pressing and microwave sintering were carried out by optical microscopy (OM) and scanning electron microscopy (SEM). Under the conditions of sintering heating rate of 20 min/°C and soaking time of 30 min at 490 °C, it was found that with the increase in Er addition, the grain size first decreased then increased, and it reached a minimum size of about 5 μm when the Er content was 0.6%, showing that the grains were refined. At the same time, the compactness and microhardness reached maximum levels, which were 97.6% and 94.5 HV, respectively. Moreover, the tensile strength and elongation reached the peak at 160.5 MPa and 4.4%, respectively. The dynamic mechanical response of Er/2024Al alloy with different Er content was studied through a split Hopkinson pressure bar (SHPB) at strain rates of 600 s−1 and 800 s−1, respectively. Both at the strain rates of 600 s−1 and 800 s−1, the dynamic yield stress of the specimens increased gradually with an increase in Er content. For the 0.6 wt.% Er specimen, the dynamic yield stress reached 371.3 MPa at a strain rate of 800 s−1, which was 28.2% higher than that at a strain rate of 600 s−1. When the strain rate is 800 s−1, the deformation degree of the 0.6 wt.%Er specimen is 55.3%, which is 14.7% higher than for the Er-free one, and there are adiabatic shear bands formed in the 0.6 wt.%Er specimen. Through a fracture analysis of the samples, a certain number of dimples appeared in the fracture of an impact specimen, indicating that the addition of Er improved the toughness of the material. This research can provide a reference for the development and application of high-performance aluminum alloy in automotive structural materials.

This paper proposes an analytical model of the double-stator spoke-type permanent magnet vernier machine (DSSTVM) using the subdomain method (SDM), which can be used to calculate the magnetic field distribution and corresponding electromagnetic parameters of the DSSTVM. The whole field domain is divided into several subdomains according to the magnetic characteristics of each region, within which Laplace’s and Poisson’s equations are solved accordingly in terms of magnetic vector potential (MVP). Then, the corresponding magnetic flux density distribution, back electromotive force (EMF), and electromagnetic torque of the DSSTVM can be obtained. Ultimately, finite element analysis (FEA) is adopted to validate the proposed analytical model’s effectiveness for quickly predicting the no-load and on-load performances of the DSSTVM.

Driven by natural and artificial selection, the domestic Huoyan geese from Northern China have gradually generated specific phenotypes and climatic adaptations. To understand the genetic basis of the two specific phenotypes that are sex linked, including upper eyelid coloboma and gosling feather color, as well as the climatic adaptations of the Huoyan goose, which can contribute to the artificial selection and breeding of geese. We selected Huoyan geese and nine Southern Chinese goose breeds and identified their divergence on the genomic level. Using selective sweep analysis, we found that PTPRM on chromosome Z influences the upper eyelid coloboma phenotype of the Huoyan goose, and TYRP1 is a plausible candidate gene for the Huoyan gosling feather color. We obtained a number of genes related to cold adaptation in Huoyan geese, mainly involved in physiological functions such as metabolism, angiogenesis contraction and circulatory system, apoptosis, immunity, stress, and neural system. The most interesting candidates for cold adaptation are PIP5K1B and NMNAT3 that are associated with energy metabolism and stress. We also obtained some genes related to heat adaptation, including AGTPBP1, associated with neurology; GDA, associated with skin pigmentation; and NAA35, associated with apoptosis. These findings deepen our understanding of the genetics of specific phenotypes and climate adaptation in local geese and provide insights for the selection of goose breeds.

Rubber concrete (RC) is a new type of concrete that is currently receiving a lot of attention, solving serious pollution problems by grinding waste tires into granules and adding them to concrete. However, rubber concrete has deficiencies in mechanics and durability, and has been reinforced by adding fibers in many studies. In this study, the mechanical and durability properties of rubber concrete with added polypropylene and basalt fibers (PBRC) were investigated in a series of experiments including apparent morphology, mass, static compressive and tensile tests, ultrasonic non-destructive testing, and scanning electron microscope (SEM) tests under coupled environments of sulfate attack and freeze–thaw. The results showed that the mass loss rate of RC and PBRC gradually increased with the number of freeze–thaw cycles, with more pits and cement paste peeling from the specimen surface. Moreover, the compressive and splitting tensile strengths of RC and PBRC groups exhibited distinct trends, with the former group showing a lower residual strength relative to the latter. The residual compressive strength of the RC group was only 69.4% after 160 freeze–thaw cycles in 5% MgSO4 solution. However, it is worth noting that the addition of too many fibers also had a negative effect on the strength of the rubber concrete. Additionally, the scanning electron microscopy (SEM) results indicated that the fibers restricted the formation of microcracks in the microstructure and curtailed the brittleness of the concrete. This study can provide a valuable reference for the application of environmentally friendly material fibers in recycled aggregate concrete.

The application of magnesium oxychloride cement (MOC) is promising, but its poor water resistance seriously hinders its development and application. In this paper, we describe a new type of MOC with excellent water resistance, prepared using fly ash and hexadecyltrimethoxysilane (HDTMS). SEM, XRD, FTIR, TG/DSC, and other microscopic-scale studies were conducted to investigate the mechanism underlying the water-resistance enhancement of the new MOC. It was found that adding 20% fly ash and 3% HDTMS can strengthen the water resistance of MOC while retaining high mechanical properties. In particular, the residual coefficient remained at 0.91 after 7 days of immersion. This is because these two additives, when used together, can increase the content of the gelling 5-phase of MOC, as well as optimize the pore structure of MOC.

This study aimed at the preparation of a 2024 aluminum alloy (2024Al) matrix composite with high strength, high toughness and high magnetic properties that can be used in practical applications. Therefore, Nd2Fe14Bp/2024Al–Co composites with different Co contents (wt.%) were prepared by ball milling, cold isostatic pressing and microwave sintering. The effects of the Co content on the microstructure, mechanical properties and magnetic properties of the prepared composites were studied. Under the conditions of the sintering temperature of 490 °C, heating rate of 20 min/°C and soaking time of 30 min, it was found that with the increase in Co content (0→2.5%→5%→7.5%→10%), the grain size first decreased and then increased, and reached the optimal value of about 3–5 μm when the Co content was 7.5%, with the microstructure being relatively uniform. At the same time, the compactness of the composite arrived at a maximum of 95.4%. The main particle phases in the composite were Nd2Fe14B, Nd2 (Fe, Co)14B and Co particles. In the nanoindentation test, the interface strength of the 7.5% Co sample was significantly higher than that of the Co-free sample. In addition, the microhardness, yield strength and compressive strength of the 7.5% Co sample were 152 HV, 210 MPa and 269 MPa, respectively, which increased by 67%, 78% and 75%, respectively, compared with the Co-free sample. With the increase in Co content, the remanence (Br), coercivity (Hcj) and maximum magnetic energy product ((BH) max) of the composites first increased and then decreased. When the Co content was 7.5%, the three performance indicators reached their optimum values, which were Br: 0.20 (T), Hcj: 4.6 (kOe) and (BH)max: 28.36 (kJ/m3). The expected goal of the lightweight magnetic materials was achieved, and the action mechanism of Co addition in the composites was also analyzed in detail.

This study constructed a two-dimensional alkaline water electrolyzer model based on the two-phase flow Euler–Euler model. In the model, the micro-nano surface electrodes with different structure types and graphic parameters (distance, height, and width) were used and compared with the vertical flat electrode to evaluate their influence on electrolysis performance. The simulation results show that the performance of the micro-nano surface electrode is much better than that of the vertical flat electrode. The total length of micro-nano structural units relates to the contact area between the electrode and the electrolyte and affects the cell voltage, overpotential, and void fraction. When rectangular structural units with a distance, height, and width of 0.5 µm, 0.5 µm, and 1 µm are used, the total length of the corresponding micro-nano surface electrode is three times that of the vertical flat electrode, and the cathode overpotential decreases by 65.31% and the void fraction increases by 54.53% when it replaces the vertical flat electrode.

An amorphous precursor of Cr2O3 pigment was prepared via solution combustion synthesis. After calcination at 1000 °C for 1.0 h, the precursor was converted into well-crystallized submicron Cr2O3 crystals with uniform particle distribution and low aggregation. Furthermore, Ti, Co, and Fe were doped into the lattice of Cr2O3, and the effects of these dopants on the reflectance spectroscopy modulation as well as chromatic properties were investigated in detail. As a result, a series of Cr2O3 pigment samples sharing similar spectra within the wavelength from 400 to 1600 nm with green plants could be successfully fabricated.

The exact mathematical modeling of electric machines has always been an effective tool for scholars to understand the working principles and structure requirements of novel machine topologies. This paper provides an analytical modeling method—the harmonic modeling method (HMM)—for two types of consequent-pole magnetic-geared machines, namely the single consequent-pole magnetic-geared machine (SCP-MGM) and the dual consequent-pole magnetic-geared machine (DCP-MGM). By dividing the whole machine domain into different ring-like subdomains and solving the Maxwell equations, the magnetic field distribution and electromagnetic parameters of the two machines can be obtained, respectively. The two machines were applied in the propulsion systems of hybrid electric vehicles (HEVs). The electromagnetic performances of two machines under different operating conditions were also compared. It turns out that the DCP-MGM can reach a larger electromagnetic torque compared to that of the SCP-MGM under the same conditions. Finally, the predicted results were verified by the finite element analysis (FEA). A good agreement can be observed between HMM and FEA. Furthermore, HMM can also be applied to the mathematical modeling of other consequent-pole electric machines in further study.

New, stable stoichiometries in Be-P systems are investigated up to 100 GPa by the CALYPSO structure prediction method. Along with the BeP2-I41/amd structure, we identify two novel compounds of Be3P2-P-421m and Be3P2-C2/m. It should be noted that the Be-P compounds are predicted to be energetically unfavorable above 40 GPa. As can be seen, interesting structures may be experimentally synthesizable at modest pressure. Our results indicate that at 33.2 GPa, the most stable ambient-pressure tetragonal Be3P2-P-421m transitions to the monoclinic Be3P2-C2/m structure. Moreover, the predicted Be3P2-P-421m and Be3P2-C2/m phases are energetically favored compared with the Be3P2-Ia-3 structure synthesized experimentally. Electronic structure calculations reveal that BeP2-I41/amd, Be3P2-P-421m, and Be3P2-C2/m are all semiconductors with a narrow band gap. The present findings offer insight and guidance for exploration toward further fundamental understanding and potential applications in the semiconductor field.