A New Method of Wind Turbine Bearing Fault Diagnosis Based on Multi-Masking Empirical Mode Decomposition and Fuzzy C-Means Clustering

Based on Multi-Masking Empirical Mode Decomposition (MMEMD) and fuzzy c-means (FCM) clustering, a new method of wind turbine bearing fault diagnosis FCM-MMEMD is proposed, which can determine the fault accurately and timely. First, FCM clustering is employed to classify the data into different clusters, which helps to estimate whether there is a fault and how many fault types there are. If fault signals exist, the fault vibration signals are then demodulated and decomposed into different frequency bands by MMEMD in order to be analyzed further. In order to overcome the mode mixing defect of empirical mode decomposition (EMD), a novel method called MMEMD is proposed. It is an improvement to masking empirical mode decomposition (MEMD). By adding multi-masking signals to the signals to be decomposed in different levels, it can restrain low-frequency components from mixing in highfrequency components effectively in the sifting process and then suppress the mode mixing. It has the advantages of easy implementation and strong ability of suppressing modal mixing. The fault type is determined by Hilbert envelope finally. The results of simulation signal decomposition showed the high performance of MMEMD. Experiments of bearing fault diagnosis in wind turbine bearing fault diagnosis proved the validity and high accuracy of the new method.

Catch bond-inspired hydrogels with repeatable and loading rate-sensitive specific adhesion

Biological receptor-ligand adhesion governed by mammalian cells involves a series of mechanochemical pro-cesses that can realize reversible,loading rate-dependent specific interfacial bonding,and even exhibit a counterintuitive behavior called catch bonds that tend to have much longer lifetimes when larger pulling forces are applied.Inspired by these catch bonds,we designed a hydrogen bonding-meditated hydrogel made from acrylic acid-N-acryloyl glycinamide(AA-NAGA)copolymers and tannic acids(TA),which formed repeatable specific adhesion to polar surfaces in an ultra-fast and robust way,but hardly adhered to nonpolar materials.It demonstrated up to five-fold increase in shear adhesive strength and interfacial adhesive toughness with external loading rates varying from 5 to 500 mm min^(-1).With a mechanochemical coupling model based on Monte Carlo simulations,we quantitatively revealed the nonlinear dependence of rate-sensitive interfacial adhesion on external loading,which was in good agreement with the experimental data.Likewise,the developed hydrogels were biocompatible,possessed antioxidant and antibacterial properties and promoted wound healing.This work not only reports a stimuli-responsive hydrogel adhesive suitable for multiple biomedical applications,but also offers an innovative strategy for bionic designs of smart hydrogels with loading rate-sensitive specific adhesion for various emerging areas including flexible electronics and soft robotics.

区块链技术在税收领域的应用：功能补拓、实践观照与问题前瞻

当前,区块链技术在税收领域的应用研究是数字经济时代税收征管创新的重点与难点问题。公开透明化、去中心化和不可变性是该技术在财税领域得以融合发展的重要支撑。国际经验表明:区块链技术在税收遵从管理、增值税与工薪税管理、虚拟货币征税、国际税收管理、海关与价值链管理等多个方面具有重要实践价值,但也面临一定的发展制约。因此,在制定具体税收政策、管理规则和技术标准时,有必要把防风险摆在突出位置,着力解决好网络安全与技术可行性、技术发展与监管挑战、区块链透明度与纳税人隐私信息保护这三类问题,从而确保数字技术创新与征管实践发展的互促共进。

Natural killer cell-derived extracellular vesicle significantly enhanced adoptive T cell therapy against solid tumors via versatilely immunomodulatory coordination

Insufficient tumor tropism,MHC classⅠmolecules(MHC-I)defects of tumor cells,and immunosuppressive tumor microenvironment(TME)seriously imperil the efficacy of adoptive T cell therapy on solid tumors.Here,natural killer cell-derived extracellular vesicle(Nev)is used as a versatile toolkit to synergistically improve adoptive T cell therapy for solid tumors.Specifically,Nev is modified with dibenzocyclooctynes(DBCO)linked with p H-sensitive benzoic-imine bonds;meanwhile,cytotoxic T lymphocyte(CTL)is decorated with azide groups.Then CTL is armed with Nev(CTL-Nev)through the click chemistry reaction.After systematic administration,Nev obviously promotes the tumor-targeting accumulation of CTL coming from its native tumor-tropism capability.Then,the cleavage of benzoic-imine bonds in the slightly acidic TME leads to the release of Nev,which not only directly induces tumor apoptosis but also promotes the action of CTL via multiplex pathways,such as up-regulating the MHC-I expression on tumor cells,reprogramming tumor-associated macrophages from pro-tumoral M2 phenotypes to tumoricidal M1 phenotypes.The all-around coordination of Nev with CTL results in potent tumor repression.