This study addresses the issue of a significant amount of unmelted powder adhering to the surface of Laser Powder Bed Fusion (LPBF) porous titanium alloy scaffolds, and the current inability of ...existing technologies to effectively handle such surface defects. Porous titanium alloy scaffolds with a triple periodical minimal surface (TPMS) Gyroid structure were prepared using powder bed fusion technology for dynamic chemical polishing. The spatial and surface morphology, as well as the mechanical properties of the scaffolds, were evaluated before and after treatment. Concurrently, fluid finite element simulation was employed to analyze the flow state of the solution inside the porous scaffold during dynamic chemical polishing. Cell culture samples were prepared and subjected to dynamic chemical polishing to study the specific effects of scaffold surface morphology on cell activity. The results indicate that the surface treatment effect, internal and external homogeneity, and dynamic and static mechanical properties of the porous scaffolds with a Gyroid structure are significantly improved after dynamic chemical polishing. Additionally, it was found that dynamic chemical polishing could effectively reduce the micrometer roughness and increase the nanometer roughness of the sample surface, thereby enhancing the adhesion, proliferation, and differentiation activities of Human Bone Mesenchymal Stem cells.
The fault diagnosis of rolling element bearing is important for improving mechanical system reliability and performance. When localized fault occurs in a bearing, the periodic impulsive feature of ...the vibration signal appears in time domain, and the corresponding bearing characteristic frequencies (BCFs) emerge in frequency domain. However, in the early stage of bearing failures, the BCFs contain very little energy and are often overwhelmed by noise and higher-level macro-structural vibrations, an effective signal processing method would be necessary to remove such corrupting noise and interference. In this paper, a new hybrid method based on optimal Morlet wavelet filter and autocorrelation enhancement is presented. First, to eliminate the frequency associated with interferential vibrations, the vibration signal is filtered with a band-pass filter determined by a Morlet wavelet whose parameters are optimized by genetic algorithm. Then, to further reduce the residual in-band noise and highlight the periodic impulsive feature, an autocorrelation enhancement algorithm is applied to the filtered signal. In the enhanced autocorrelation envelope power spectrum, only several single spectrum lines would be left, which is very simple for operator to identify the bearing fault type. Moreover, the proposed method can be conducted in an almost automatic way. The results obtained from simulated and practical experiments prove that the proposed method is very effective for bearing faults diagnosis.
This study addresses the challenges of accurately analyzing the reliability of aviation power systems (APS) using traditional models by introducing the Aviation Power System Reliability Probability ...Network Model (APS-RPNM). The model directly transforms the system architecture into an equivalent probability network, aiming to develop a precise reliability model that captures system functions and fault logic. By classifying APS components into five distinct structural patterns and mapping them to corresponding nodes in the APS-RPNM, the model is successfully constructed. Specifically, None-Input-to-Multiple-Output components are transformed into two-state nodes, while Multiple-Input-to-None-Output, Single-Input-to-Multiple-Output, and Multiple-Input-to-Single-Output components are mapped to three-state nodes. For Multiple-Input-to-Multiple-Output components, a novel approach employing multiple two-state sub-nodes is adopted to capture their complex functional logic. A case study comparing the performance of the APS-RPNM with the traditional minimal path set method in reliability analysis was conducted. The results demonstrate that the APS-RPNM not only simplifies the model construction process and eliminates errors stemming from subjective engineering judgments but also enables the efficient computation of power supply reliability for all load points in a single inference by integrating all of the components. This significantly improves computational efficiency and system dependency analysis capabilities, highlighting the APS-RPNM’s tremendous potential in optimizing the reliability design of APS.
A simulation method for the wear of a dynamic seal in an axial flux hub motor is proposed in this work. A quasi-3D magnetic model without deflection between the axes of a stator and a rotor is built. ...An analytical model for unbalanced magnetic force considering the cogging effect and axial deflection is presented based on the quasi-3D magnetic model. Boundary conditions of the dynamic seal are obtained through solving the FE model of a hub motor. Both the structural and thermal FE model of a dynamic seal are built and the thermal–structural coupling method is given. A dynamic wear simulation method is displayed based on the mesh reconstruction method proposed previously. It is proved through the contrast with the experimental results that the presented method is feasible.
Abstract Fungal diseases, such as powdery mildew and rusts, significantly affect the quality and yield of wheat. Pyramiding diverse types of resistance genes into cultivars represents the preferred ...strategy to combat these diseases. Moreover, achieving collaborative improvement between diseases resistance, abiotic stress, quality, and agronomic and yield traits is difficult in genetic breeding. In this study, the wheat cultivar, Guinong 29 (GN29), showed high resistance to powdery mildew and stripe rust at both seedling and adult plant stages, and was susceptible to leaf rust at the seedling stage but slow resistance at the adult-plant stage. Meanwhile, it has elite agronomic and yield traits, indicating promising coordination ability among multiple diseases resistance and other key breeding traits. To determine the genetic basis of these elite traits, GN29 was tested with 113 molecular markers for 98 genes associated with diseases resistance, stress tolerance, quality, and adaptability. The results indicated that two powdery mildew resistance ( Pm ) genes, Pm2 and Pm21 , confirmed the outstanding resistance to powdery mildew through genetic analysis, marker detection, genomic in situ hybridization (GISH), non-denaturing fluorescence in situ hybridization (ND-FISH), and homology-based cloning; the stripe rust resistance ( Yr ) gene Yr26 and leaf rust resistance ( Lr ) genes Lr1 and Lr46 conferred the stripe rust and slow leaf rust resistance in GN29, respectively. Meanwhile, GN29 carries dwarfing genes Rht-B1b and Rht-D1a , vernalization genes vrn-A1 , vrn-B1 , vrn-D1 , and vrn-B3 , which were consistent with the phenotypic traits in dwarf characteristic and semi-winter property; carries genes Dreb1 and Ta-CRT for stress tolerance to drought, salinity, low temperature, and abscisic acid (ABA), suggesting that GN29 may also have elite stress-tolerance ability; and carries two low-molecular-weight glutenin subunit genes Glu-B3b and Glu-B3bef which contributed to high baking quality. This study not only elucidated the genetic basis of the elite traits in GN29 but also verified the capability for harmonious improvement in both multiple diseases resistance and other comprehensive traits, offering valuable information for breeding breakthrough-resistant cultivars.
f. sp.
(
) is adept at overcoming resistance in wheat cultivars, through variations in virulence in the western provinces of China. To apply disease management strategies, it is essential to ...understand the temporal and spatial dynamics of
populations. This study aimed to evaluate the virulence and molecular diversity of 84 old
isolates, in comparison to 59 newer ones. By using 19 Chinese wheat differentials, we identified 98 pathotypes, showing virulence complexity ranging from 0 to 16. Associations between 23
gene pairs showed linkage disequilibrium and have the potential for gene pyramiding. The new
isolates had a higher number of polymorphic alleles (1.97), while the older isolates had a slightly higher number of effective alleles, Shannon's information, and diversity. The Gansu
population had the highest diversity (
= 0.35), while the Guizhou population was the least diverse. Analysis of molecular variance revealed that 94% of the observed variation occurred within
populations across the four provinces, while 6% was attributed to differences among populations. Overall,
populations displayed a higher pathotypic diversity of
> 2.5 and a genotypic diversity of 96%. This underscores the need to develop gene-pyramided cultivars to enhance the durability of resistance.
The sliding of the rolling element in the load zone would cause the bearing’s wear and failure at high speed under elastohydrodynamic lubrication (EHL) condition. Aiming at this phenomenon, ...considering lubrication oil film, time-varying displacement, radial clearance, and comprehensive stiffness, a five degree-of-freedom (DOF) dynamic model of rolling bearing with local defect is proposed based on isothermal EHL and which is validated by experimental data. The variation of oil film stiffness, comprehensive stiffness, and vibration characteristics of rolling bearing is studied under different speeds and loads. The results show that the lubricating oils with different viscosities have a certain influence on the bearing oil film thickness and comprehensive stiffness. As the load increases, the oil film stiffness and comprehensive stiffness would increase, and the oil film thickness would decrease. And as the tangential speed increases, the oil film stiffness would increase, and the oil film thickness and comprehensive stiffness would decrease. The vibration amplitude of the rolling bearing is enhanced with the increase of the rotation speed and the radial load. This model is helpful for the optimization, the correct use of lubricants, and life prediction of rolling bearing.
In this paper, a simulation model for Selective Laser Melting (SLM) technology is established to simulate the additive manufacturing process of a turbine impeller for an aerospace engine. By ...utilizing the simulation model, variations in laser power and scanning speed are employed to obtain simulated results of thermal deformation for the turbine impeller under different laser power and scanning speed conditions. The results indicate that the thermal deformation of the component increases with the augmentation of laser power, decreases with the escalation of scanning speed, and eventually stabilizes. Based on the relationship between thermal deformation and energy, the energy utilization efficiency of the SLM process under different conditions is calculated. The findings demonstrate that, within a certain range of power, the synergistic effect of laser power and scanning speed allows for an increase in energy utilization efficiency and a reduction in processing time while ensuring the mechanical performance of the formed parts. Consequently, this approach proves effective in lowering production costs for complex components based on SLM technology.
The bearing-rotor-gear system is an important mechanical component for transmitting motion and power. Due to the complex responses, the condition assessment of the transmission system becomes more ...difficult. Thus, a model of the bearing-rotor-gear system with a misaligned rotor is built for implementing the complex response analysis. The misalignment rotor is realized by offset connection of couplings, and the creative excitation force is transferred to the bearing inner ring through the rotor. The constructed model is checked by the corresponding experiment. From the simulation results, it is found that vibration responses are modulated by rotor frequencies, and there are rotor frequencies, harmonic frequencies of bearings, and gear pairs in the spectrum. When the misalignment defect is deepening, the high-order harmonic responses are excited. If the revolving speed increases, the modulation of the rotor frequencies is accentuated, the vibration intensity generated by gear pairs is attenuated, while the harmonic response and super-harmonic response of bearings can be suppressed, and the system vibrates mainly at the low-frequency band. When the load becomes higher, the amplitudes of the rotor frequencies, meshing frequencies, and defect frequencies are all increased.
The leakage prediction calculation method for dynamic seal rings in underground equipment is presented in this paper. The framework of the method is given. The leakage prediction model is built. The ...non-Newtonian fluid interface element is brought in. The leakage prediction calculation method was developed based on the thermal–structural coupled method and the fluid–structural coupled method. A test is performed to validate the proposed method. It is proved that the film thickness of an O-ring made of nitrile rubber in pulling-in travel is thicker than that in pushing-out travel. The leakage of an O-ring made of fluororubber is larger than that of an O-ring made of nitrile rubber in the same environmental condition. The presented method is useful for predicting the sealing ability of dynamic seal rings in underground equipment. Evaluation costs will be reduced with the given leakage prediction calculation method.
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