不确定性下Bayes-DeepONet旋转机械故障报警方法研究

深度学习方法在旋转机械故障诊断中得到广泛应用,但现有的方法很少考虑数据和模型不确定性对诊断结果的影响,以致于实际应用中模型的泛化能力不足,精度无法保证。本文基于Dropout的近似变分推理与深度算子神经网络(DeepONet)模型无缝对接,提出一种基于不确定性下贝叶斯DeepONet模型的旋转机械故障预警新模型。使用大型压缩机案例,进行了方法验证,结果表明:考虑数据和模型的不确定性,所提方法具有非常高的准确性,实现对机组运行状态的实时监测和精准预警。

Hot tensile deformation behavior and globularization mechanism of bimodal microstructured Ti-6Al-2Zr-1Mo-1V alloy

The hot deformation behavior,microstructure evolution and fracture characteristics of bimodal microstructured Ti-6Al-2Zr-1Mo-1V alloy were investigated by isothermal tensile tests.Results reveal that flow softening is caused by dynamic globularization of the bimodal microstructure,which also results in a relatively high stress exponent and thermal activation energy.The corresponding SEM,EBSD and TEM observations indicate that the dynamic globularization at750and800℃is accomplished by the formation ofα/αsub-grain boundary and penetration of theβphase.However,dynamic recrystallization(DRX)is the main globularization mechanism at850℃,which was proved by the generation of fine grains with a necklace-like character due to the transformation of low-angle boundaries(LABs)into high-angle boundaries(HABs).With an increase in the deformation temperature or a decrease in the strain rate,the fracture mechanism changes from microvoid coalescence to intergranular fracture.

Dehydroabietic acid chemosensitizes drug-resistant acute lymphoblastic leukemia cells by downregulating survivin expression

Objective:To explore the mechanism of drug resistance in acute lymphoblastic leukemia and the anti-tumor effect of combination therapy of dehydroabietic acid and vincristine against acute lymphoblastic leukemia cells.Methods:Acute lymphoblastic leukemia cells REH and CCRFCEM were employed to detect the anti-tumor effect of vincristine and doxorubicin on proliferation and apoptosis using EdU assay,human active caspase-3 Quantikine ELISA kit,and flow cytometry.Vincristine-resistant REH cells(REH-R),survivin knockdown and overexpressing REH cells were established to verify the role of survivin in drug resistance.Additionally,in vitro and in vivo assays were performed to determine the effect of dehydroabietic acid on the cytotoxicity of vincristine.Results:Vincristine and doxorubicin markedly suppressed proliferation and induced apoptosis of REH and CCRF-CEM cells.Survivin expression was upregulated in REH-R cells compared with REH cells.Knockdown of survivin expression obviously restored the sensitivity of REH-R cells to vincristine.Akt phosphorylation was also increased in REH-R cells compared to REH cells.In addition,LY294002,a PI3k/Akt pathway blocker,inhibited survivin expression and enhanced cytotoxicity of vincristine to REH-R cells.Dehydroabietic acid effectively reduced survivin expression in REH-R cells,thereby enhancing the therapeutic effect of vincristine on drug-resistant cells.Survivin overexpression markedly reduced the effect of dehydroabietic acid on enhancing the anti-proliferation and inducing apoptosis effect of vincristine.Moreover,the combination of dehydroabietic acid with vincristine significantly extended the survival rate in a mouse xenograft model of acute lymphoblastic leukemia,compared with vincristine treatment alone.Conclusions:Dehydroabietic acid may be used as a potential candidate for the treatment of acute lymphoblastic leukemia in combination with vincristine.

Ductile fracture behavior of TA15 titanium alloy at elevated temperatures

To better understand the fracture behavior of TA15 titanium alloy during hot forming, three groups of experiments were conducted to investigate the influence of deformation temperature, strain rate, initial microstructure, and stress triaxiality on the fracture behavior of TA15 titanium alloy. The microstructure and fracture surface of the alloy were observed by scanning electronic microscopy to analyze the potential fracture mechanisms under the experimental deformation conditions. The experimental results indicate that the fracture strain increases with increasing deformation temperature, decreasing strain rate, and decreasing stress triaxiality. Fracture is mainly caused by the nucleation, growth, and coalescence of microvoids because of the breakdown of compatibility requirements at the α/β interface. In the equiaxed microstructure, the fracture strain decreases with decreasing volume fraction of the primary α-phase(αp) and increasing α/β-interface length. In the bimodal microstructure, the fracture strain is mainly affected by α-lamella width.

Effects of Proton Pump Inhibitors on the Gastrointestinal Microbiota in Gastroesophageal Reflux Disease

Proton pump inhibitors(PPIs) are commonly used to lessen symptoms in patients with gastroesophageal reflux disease(GERD). However, the effects of PPI therapy on the gastrointestinal microbiota in GERD patients remain unclear. We examined the association between the PPI usage and the microbiota present in gastric mucosal and fecal samples from GERD patients and healthy controls(HCs) using 16 S rRNA gene sequencing. GERD patients taking PPIs were further divided into short-term and long-term PPI user groups. We showed that PPI administration lowered the relative bacterial diversity of the gastric microbiota in GERD patients. Compared to the non-PPIuser and HC groups, higher abundances of Planococcaceae, Oxalobacteraceae, and Sphingomonadaceae were found in the gastric microbiota from the PPI-user group. In addition, the Methylophilus genus was more highly abundant in the long-term PPI user group than in the short-term PPI-user group. Despite the absence of differences in alpha diversity, there were significant differences in the fecal bacterial composition of between GERD patients taking PPIs and those not taking PPIs. There was a higher abundance of Streptococcaceae, Veillonellaceae, Acidaminococcaceae,Micrococcaceae, and Flavobacteriaceae present in the fecal microbiota from the PPI-user group than those from the non-PPI-user and HC groups. Additionally, a significantly higher abundance of Ruminococcus was found in GERD patients on long-term PPI medication than that on shortterm PPI medication. Our study indicates that PPI administration in patients with GERD has a significant effect on the abundance and structure of the gastric mucosal microbiota but only on the composition of the fecal microbiota.

Dynamic terahertz anisotropy and chirality enhancement in liquid-crystal anisotropic dielectric metasurfaces

To enhance and actively control terahertz(THz) anisotropy and chirality, we have designed and fabricated a THz composite device with a liquid crystal(LC) layer and Si anisotropic metasurface. By initial anchoring and electrically rotating the spatial orientation of the LC optical axis, the different symmetry relationships are obtained in this hybrid device. When the optical axis of LC is parallel or perpendicular to the optical axis of the Si metasurface, the anisotropy of the device will be enhanced or offset, which leads to a tunable phase-shift range of more than 180°. When there is an angle between the two optical axes, due to the destruction of the mirror symmetry in the LC-Si anisotropic medium, the highest circular dichroism of the device reaches 30 dB in the middle orientation state of the LC optical axis, and the active modulation can be realized by changing the bias electric field on the LC layer. This composite device demonstrates rich characteristics for the feasible manipulation of THz polarization conversion and chiral transmission, which can be applied in THz polarization imaging and chiral spectroscopy.

Active terahertz beam manipulation with photonic spin conversion based on a liquid crystal Pancharatnam–Berry metadevice

Active terahertz (THz) beam manipulation is urgently needed for applications in wireless communication, radar detection, and remote sensing. In this work, we demonstrate a liquid crystal (LC) integrated Pancharatnam–Berry(PB) metadevice for active THz beam manipulation. Through theoretical analysis and simulation design, the geometric phase of the PB metasurface is engineered to match the tunable anisotropic phase shift of LCs under an external magnetic field, and dynamic beam deflection accompanied by spin conversion is obtained. The experimental results show that the device realizes a dynamic modulation depth of >94% and maximum efficiency of over 50% for the different spin states. Moreover, due to the broadband operating characteristics of devices at 0.7–1.3 THz, the deflection angles are frequency dependent with a scanning range of over ±20° to ±32.5°.Moreover, the two conjugate spin states are always spatially separated in different deflection directions with an isolation degree of over 10 dB. Therefore, this metadevice provides a scheme of active THz beam deflection and spin state conversion, and it also achieves both controllable wavelength division multiplexing and spin division multiplexing, which have important potential in large-capacity THz wireless communication.