Experimental investigation of rotordynamic coefficients for the labyrinth seals with and without shunt injection

Shunt injection serves an important role in the labyrinth seal static and rotordynamic characteristics which are important in the prediction of turbomachinery stability. This paper analyzed how the shunt injection affects the seal rotordynamic characteristics, and presented an improved impedance method based on unbalanced synchronous excitation to identify the rotordynamic coefficients of labyrinth seals on a rotor test rig. The influences of the rotational speed and the inlet/outlet pressure ratio on the rotordynamic characteristics of shunt injection seals with and without shunt injection were identified and analyzed. The experimental results reveal that all the seal rotordynamic coefficients increase with the rotational speed, and the inlet/outlet pressure ratio. The shunt injection contributes to decreasing the seal cross-coupled stiffness, and increasing the direct damping. The shunt injection plays an important role in decreasing the effective stiffness coefficient, and increasing the effective damping coefficient. The shunt injection can effectively improve the rotor stability. The experimental results lay the foundation for designing the annular seals with shunt injection

MLA-BIN: Model-level Attention and Batch-instance Style Normalization for Domain Generalization of Federated Learning on Medical Image Segmentation

The privacy protection mechanism of federated learning (FL) offers an effective solution for cross-center medical collaboration and data sharing. In multi-site medical image segmentation, each medical site serves as a client of FL, and its data naturally forms a domain. FL supplies the possibility to improve the performance of seen domains model. However, there is a problem of domain generalization (DG) in the actual de-ployment, that is, the performance of the model trained by FL in unseen domains will decrease. Hence, MLA-BIN is proposed to solve the DG of FL in this study. Specifically, the model-level attention module (MLA) and batch-instance style normalization (BIN) block were designed. The MLA represents the unseen domain as a linear combination of seen domain models. The atten-tion mechanism is introduced for the weighting coefficient to obtain the optimal coefficient ac-cording to the similarity of inter-domain data features. MLA enables the global model to gen-eralize to unseen domain. In the BIN block, batch normalization (BN) and instance normalization (IN) are combined to perform the shallow layers of the segmentation network for style normali-zation, solving the influence of inter-domain image style differences on DG. The extensive experimental results of two medical image seg-mentation tasks demonstrate that the proposed MLA-BIN outperforms state-of-the-art methods.Comment: 9 pages, 8 figures, 2 table

Disinfection efficacy of green synthesized gold nanoparticles for medical disinfection applications

Background: In recent times, biosyntheses of metal nanoparticles were used for several life rescue applications. In this study, Dillenia indica leaf aqueous extract was utilized for the synthesis of gold nanoparticles.Objective: To test anti-microbial properties of biologically fabricated gold nanoparticles.Methods: Gold nanoparticles were efficiently prepared by making use of aqueous leaf extract of Dillenia indica. The excitation of formed AuNPs was confirmed using UV–Vis spectrophotometer. In particular, absorption spectra of AuNPs exhibited a well-defined SPR band centered at around 530 nm.Results: The high-resolution Scanning Electron Microscope (SEM) results of the obtained AuNPs confirmed the formation of particles with a size range of 5–50 nm. The ultra-high resolution TEM (UHRTEM) images displayed clear lattice fringes on the particle surfaces. Single crystalline nature of the biosynthesized AuNPs was represented by means of selected-area electron diffraction pattern.Conclusion: The antibacterial activity of AuNPs revealed significant activity towards both gram negative and gram positive bacteria signifying their potential disinfection related applications in medicine and biology.Keywords: Dillenia indica leaves, disinfection, AuNPs