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This paper focuses on the trajectory tracking issue of the pneumatic artificial muscle (PAM) exoskeleton system. First of all, a new type of the PAM elbow exoskeleton was introduced to assist wearers in elbow flexion/extension movement. Moreover, a model-free adaptive control approach was combined with the prescribed performance control to ensure the tracking errors to be converged to the predefined requirements. Meanwhile, to suffer the influence of the unknown external disturbance on the exoskeleton, a terminal sliding mode control was adopted to reduce the tracking errors. From a theoretical perspective, the stability of the proposed controller can be proved by Lyapunov synthesis. After two sets of experiments, the proposed control method can further improve the tracking accuracy in the PAM elbow exoskeleton, compared with the other three model-free adaptive control methods. Simultaneously, the maximum absolute value of the tracking errors never exceeded the designed boundary. [ABSTRACT FROM AUTHOR]

In recent years, the growing popularity of artificial neural networks has urged more and more researchers to try introduce these methods to the machining field, with some of them actually producing good results. The acquisition of cutting data often means higher cost and time, limiting the application of neural network in the machining sector, to a certain extent. In this paper, for the task of cutting force prediction, a "transfer network" was established, based on data obtained by simulation, combined with the theory and method in the field of transfer learning. Compared to "ordinary network", that is, traditional back-propagation neural network based on experimental samples alone, transfer network exhibits obvious performance advantages. On one hand, this means that, using the same experimental samples, the prediction error of transfer network will be controlled; while on the other hand, when the same prediction error is achieved, the number of experimental samples required by the transfer network will be less. [ABSTRACT FROM AUTHOR]

Leaf morphology varies significantly among Brassica juncea. However, little is known regarding the causal gene that controls lobed leaf shape in B. juncea. In our study, the BjRCO gene, which is associated with leaf morphological variation, was cloned from chromosome A10 in B. juncea via BSR-seq. Blast analysis suggested that the BjRCO encodes a HD-Zip I transcription factor, which may serve as a positive regulator of lobed leaf formation in leaf mustard. Interestingly, the lobed leaf genes reported in the related species of Brassica (B. rapa, B. napus, and B. juncea) were located in A10. Phylogenetic analysis showed that BjRCO was also homologous to the lobed leaf gene BoLl reported on chromosome 9 in B. oleracea. In addition, qRT-PCR results showed that the expression levels of the BjRCO gene were higher expressed in the inner small lobed leaves than in the little sawtooth-like leaves (LSL). These results of this study indicate that the BjRCO gene is related to lobed leaf formation in B. juncea. These findings help to establish a solid foundation for future research investigating the molecular mechanism governing lobed leaf formation in B. juncea. [ABSTRACT FROM AUTHOR]

The drug-release time of suture should meet with the healing time of wound, so it is needed to control the drugrelease performance of polylactic acid (PLA) suture. In this paper, two biodegradable polymers with different degradation rates, such as polycaprolactone (PCL) and polyglycolide (PGA), were applied to carry the drug of tea polyphenol (TP). The drug-loading finishing solution which is made of PCL/PGA carriers and TP, was coated on the PLA suture. The drug-release rate and time of PLA suture could be regulated by adjusting the proportion of PCL/PGA carriers. The results indicate that the surface of drug-loaded PLA suture becomes rough. There is no obvious chemical reaction among the drug, carriers and PLA suture, just physical adhesion. With the increasing of PCL in drug-carriers, the strength of suture gradually increases. At 70/30 of PCL/PGA, the fracture elongation of suture reaches the highest point. In process of degradation, the surface of drugloaded PLA suture appears some holes after 25 weeks. The strength of sutures decreases gradually during degradation, and the effective strength time of sutures with various proportions of PCL/PGA is different. The drug-release rate of the suture is fast at early stage and slow at later stage and the higher the PGA proportion is, the faster the drug-release rate of the suture is. [ABSTRACT FROM AUTHOR]

Pinhole drying process is a slowly dryness in the air caused by capillary force. It was found useful to improve the transparency of silica aerogel. So in this work, pinhole drying was considered as a modification on the microstructure. We studied the effect of pinhole drying on the light transmission of aerogel. The effect of pinhole drying on the microstructure of aerogel was also investigated. The spherical transmittance ( τ ) and directional transmittance ( τ ) were measured by ultraviolet-Visible-infrared spectrophotometer, the scattering light at the 90° direction of the gel was measured by a nephelometer, and the microstructure of the aerogels were analyzed applying small angle X-ray scattering, nitrogen adsorption porosimetry, and scanning electron microscope. The results showed that pinhole dried silica aerogels and non-pinhole dried aerogels exhibited different microstructure and optical properties. The directional transmittance of the pinhole dried aerogel and non-pinhole dried aerogel at 600 nm wavelength was 57.9 and 40.9%, respectively, an improvement of 17.0%. The transparency ratio ( τ / τ ) of pinhole dried aerogel and non-pinhole dried aerogel at 400 nm wavelength was 0.26 and 0.07, respectively, an improvement of 0.19. Small angle X-ray scattering measurements showed that these improvements can be attributed to the smaller mean cluster size of pinhole dried aerogels than that of non-pinhole dried aerogels. 90° scattering light experiments indicated that the clusters of the gel were becoming smaller during the drying process caused by capillary force according to Rayleigh scattering theory. It is the reason why pinhole dried aerogels have smaller mean cluster size and relatively transparent. Graphical Abstract: [ABSTRACT FROM AUTHOR]

A large number of electronic devices could generate a lot of electromagnetic waves, which could interfere with other equipment and harm the human body. Therefore, an electromagnetic interference shielding (EMI) material is urgently needed to protect the human body and the electronic equipment. In this paper, the multi-wall carbon nanotubes (MWCNTs) and the nano-Fe3O4 were added into the polylactic acid (PLA) matrix to form the composite film with electromagnetic interference shielding performance. And the structure and properties of MWCNTs/Fe3O4/PLA composite films, such as the morphology, chemical structure, crystallization, mechanical property, conductive property, magnetic property and electromagnetic interference shielding property, were researched. The result shows that too much Fe3O4 could lead to agglomeration, and the coupling agent KH570 had grafted and modified the surface of MWCNTs. The MWCNTs and nano-Fe3O4 could increase the crystallinity of PLA matrix. With the increase of MWCNTs, the maximum tensile stress of composite films gradually increased, and the maximum tensile strain decreased, and the resistance value showed a significant downward trend. The Fe3O4 could improve the magnetic properties of composite film. The MWCNTs and Fe3O4 could improve the electromagnetic interference shielding efficiency (EMI SE). The MWCNTs played a more significant role than the Fe3O4 in the process of EMI, and the EMI SE of the composite film with 3:1 ratios of MWCNTs/Fe3O4 could rise to 22 dB. [ABSTRACT FROM AUTHOR]