HMM-Based Method for Aircraft Environmental Control System Turbofan Rolling Bearing Fault Diagnosis

In response to the high-noise, nonlinear, and nonstationary characteristics of vibration signals from aircraft environmental control system (ECS) turbofan rolling bearings, this paper proposes a diagnostic method for the degree of ECS turbofan bearing faults based on the Hidden Markov Model (HMM). Experimental results demonstrate that HMM can accurately diagnose and predict faults in ECS turbofan rolling bearings. The HMM method enhances diagnostic accuracy, and its effectiveness and feasibility in fault diagnosis based on different rolling bearing fault instances are elaborated. By employing the HMM model to establish precise models from decomposed dynamic data, it successfully identifies faults such as the fracture of the bearing cage under biased load conditions, although its performance in recognizing overheating faults is suboptimal

Preparation and characterization of different micro/nano structures on the surface of bredigite scaffolds

Abstract The preparation of controllable micro/nano structures on the surface of the bredigite scaffold is expected to exhibit the same support and osteoconductive capabilities as living bone. However, the hydrophobicity of the white calciμm silicate scaffold surface restricts the adhesion and spreading of osteoblasts. Furthermore, during the degradation process of the bredigite scaffold, the release of Ca2+ results in an alkaline environment around the scaffold, which inhibits the growth of osteoblasts. In this study, the three-dimensional geometry of the Primitive surface in the three-periodic minimal surface with an average curvature of 0 was used as the basis for the scaffold unit cell, and a white hydroxyapatite scaffold was fabricated via photopolymerization-based 3D printing. Nanoparticles, microparticles, and micro-sheet structures with thicknesses of 6 μm, 24 μm, and 42 μm, respectively, were prepared on the surface of the porous scaffold through a hydrothermal reaction. The results of the study indicate that the micro/nano surface did not affect the morphology and mineralization ability of the macroporous scaffold. However, the transition from hydrophobic to hydrophilic resulted in a rougher surface and an increase in compressive strength from 45 to 59–86 MPa, while the adhesion of the micro/nano structures enhanced the scaffold's ductility. In addition, after 8 days of degradation, the pH of the degradation solution decreased from 8.6 to around 7.6, which is more suitable for cell growth in the hμman body. However, there were issues of slow degradation and high P element concentration in the degradation solution for the microscale layer group during the degradation process, so the nanoparticle and microparticle group scaffolds could provide effective support and a suitable environment for bone tissue repair

Optimization of mechanical and damping properties of Mg–0.6Zr alloy by different extrusion processing

In this study, the optimization of mechanical and damping capacities of Mg-0.6 wt.% Zr alloys by controlling the recrystallized (DRXed) grain size under varying extrusion processing parameters including extrusion temperature T and strain rate ε˙ was investigated. The relationship between the DRXed grain size and damping properties of the studied alloy was also discussed. The DRXed grain size of the as-extruded Mg–Zr alloys decreased as the extrusion temperature T decreased and the strain rate ε˙ increased. As the DRXed grain size decreased, the strength and elongation of the as-extruded alloys exhibited improved performance through the grain refinement mechanism, while the damping properties deteriorated. The extrusion temperature of the Mg–Zr alloy had relatively greater effects on the mechanical and damping properties than the strain rate. The results of the present work indicate that alloys with appropriate mechanical and damping properties may be obtained from controlling the DRXed grain size by careful tailoring of the extrusion process parameters

Additional file 1 of Functional characterization of a farnesyl diphosphate synthase from Dendrobium nobile Lindl

Additional file 1: Table S1. Primers used in thisstudy. Primer sequences for the restriction sites are shown in bold. Table S2.Relevant FPPSs sequences for phylogenetic analysis. Table S3. a. Correlationanalysis between AACT and FPPS. b. Correlation analysis between HMGR and FPPS. c.Correlation analysis between HMGS and FPPS. d. Correlation analysis between MK andFPPS. e. Correlation analysis between PMK and FPPS. f. Correlation analysisbetween MVD and FPPS. g. Correlation analysis between TPS21 and FPPS. Fig.S1 The MVA and MEP pathways are the main steps in the synthesis ofdendrobine. Fig. S2. The relative expression of DnFPPS atdifferent tissues in D.nobile. Fig. S3 Agarose gelelectrophoresis of the core fragment amplification products of Dnfpps. Fig. S4 The relative expression ofdifferent genes at different time points in D.nobile after MeJAtreatment