Dynamic parameters of joints are indispensable factors affecting performance of machine tools. In order to obtain the stiffness and damping of sliding joints between the working platform and the machine tool body of the surface grinder, a new method of dynamic parameters identification is proposed that based on deep neural network (DNN) modeling. Firstly, the DNN model of dynamic parameters for working platform-machine tool body sliding joints is established by taking the stiffness and damping parameters as the input and the natural frequencies as the output. Secondly, the number of hidden layers in DNN topology is optimally selected in order to the optimal training results. Thirdly, combining the predicted results by DNN model with experimental results by modal test, the stiffness and damping are identified via cuckoo search algorithm. Finally, the relative error between the predicted and experimental results is less than 2.2%, which achieves extremely high prediction precision; and thereby indicates the feasibility and effectiveness of the proposed method.

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An efficient and facile cyclic iminium-ion-based strategy has been developed for the synthesis of structurally diverse N-aryl substituted C1-functionalized THIQs. Cyclic iminium ions generated in situ from 2-(2-bromomethyl)benzaldehyde reacted with acetone to furnish ketone moiety at C-1 position in THIQs in moderate to good yields.The 1,2,3,4-tetrahydroisoquinoline (THIQ) structural motif, especially C1-substituted THIQs, is active structural unit in natural products, pharmaceuticals, and exhibits a wide range of biological activities, including anticancer activities, 2 anti-inflammatory, 3 antimicrobial, 4 and anti-plasmodial activities.Representative examples (Figure 1) include (+)-dysoxyline (A), isolated from Dysoxylum lenticellare, Praziquantel (B), a broad-spectrum antischistosomal agent, 7 and Lifitegrast (C), a novel integrin antagonist marketed in 2016 for the treatment of dry eye disease, 8 Moreover, drug candidate BMS-962212 (D), a reversible, direct, and highly selective small molecule inbibtor of factor XIa in phase